I dunno, the last sheet of plywood I bought was still 4x8 foot. It was even 3/4" thick when I measured it with my metric/SAE electronic calipers. My ceilings though are still 8 foot. I don’t mind I guess because I’m short and would have no trouble fitting in a metric house. I envision someday someone posting a picture of a 9/16" wrench and asking what is it? I will be dead by that time though.
Fractions are difficult. In 8th grade metal shop I thought it was silly to spend an entire class period learning how to use a ruler/tape measure. Out of 15 students 6 had no clue. It was obviously not the instructors first rodeo. Metric and SAE are both useable. The biggest problems I have seen is people trying to convert one to the other. I also recall domestic vehicles with a mixture of metric/SAE fasteners.
I wasn’t joking. Most of us, if not all, had to deal with teachers in school who insisted on doing metric conversions to the Nth decimal place. And we didn’t have calculators when I as in school, you younger ones probably weren’t allowed to use your calculators in the classroom.
I think if people realized that doing the conversions is completely unnecessary, just use the proper measuring equipment/device and it would be a lot easier to accept the metric system.
It would help if our own government started using the metric system, they are the biggest obstacle to its adoption right now.
Let’s see, 7 feet is 84 inches plus 6.625 inches makes the length 90.625 inches long. Divide that by three and each third will be 30.208 inches.
That assumes zero loss from saw kerf. However there is no such thing as a zero kerf saw so we need to take that into account. Let’s say your Skil Saw blade cuts a 1/8 inch kerf (.125"), that’s .25 inches lost from the two cuts so we need to subtract .25 inches from 90.625 leaving 90.375 inches to divide by three, that comes out to 30.125 inches per piece or 30 1/8 inches. It’s not that hard really.
Yes, inches can be decimalized. I have a dial caliper that measures inches, tenths of inches, hundreths of inches, and thousanths of inches. They also make decimal rulers in inches with tenths instead of sixteenths.
I get what you’re saying, now, and I agree completely. I remember the emphasis on conversions.
I have fun when people complain that it took a long time to learn our units of measure, pounds, gallons, yards, etcetera, and they don’t want to go through the trouble learning the metric system.
I give them a few quiz questions. How many cups in a quart? How many ounces in a gallon? How many feet in a mile, pounds in a ton, ounces in a quarter of a pint? 
It is surprising (or not) how many people never learned what they think they learned.
Also, a great many folks are not good with fractions
or comfortable with a mix of different denominators.
Most folks don’t have a problem with 100.00, 50.00, 20.00, 10.00, 5.00, 1.00, .50, .25, .10, .05, and .01, especially when they appear with a dollar sign in front. 
CSA
Yes. Our official monetary denominations are metric. Their slang is as convoluted to foreigners as English monetary slang. With our Dollar, Half Dollar (self explanatory), Quarter, Dime, Nickel, and penny.
There are easier non-math ways. Just lay the tape at a diagonal. No math needed.
http://lumberjocks.com/GnarlyErik/blog/33282
20 years ago I went to the ER with pain in my lower abdomen, turned into emergency surgery to remove some diseased colon. The surgery was on a Friday evening, and when I came to I was in excruciating pain, the morphine drip wasn’t doing a thing. I was in agony all weekend until the surgeon did his rounds Monday. He examined the chart and said “Oh, here’s the problem. They entered your weight in kg instead of lbs when calculating your medication. You should be getting 2.2 times the morphine than you are.”
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That mistake was made on a Canadair flight and the pilot had to make a dead-stick landing half way to Vancouver. Also, a Mars probe crashed because pounds were confused with newtons for the thrusters.
We have decimal currency, not metric. There’s no such thing as metric currency.
I have a ruler marked off in decimal inches. Inches divided into tenths instead of 16ths. That doesn’t make it metric.
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If you had asked me, I would have gotten every one of them right.
Seems like the rest of the world has no problems with time that’s measured in days, hours, minutes, and seconds. Angles that are measured in degrees, minutes, and seconds, and a screwy temperature scale where you have plus and minus temperatures even in the range of normal weather temperatures.
In engineering we have things marked in 1/10ths of feet, thus 10 tenths = 1 foot, it is really hard to explain why a foot = 10 tenths, and these are not inches to some newbies who measure 1.5 and think it means one foot 5 inches, instead of 1 foot 5 tenths, meaning a half of a foot or 1’ 6 inches.
You could just say 1.5 feet and it would make sense. Although nothing surprises me anymore.
So my first gig out of drafting school, Make me a print the boss says, architectural scale is different than engineering scale, architectural is in 1/8" 1/4" to a foot etc., whatever engineering is in 1/10 1/2o 1/30 to a foot whatever.
So not knowing any better he said make it any scale you want, I thought 1" on the plan = 75’ sounds nice. Well he was like we were trying to scale out the prints what the hell scale did you make it? I said 1 " = 75 feet, Why did you do that, we could not figure it out, I thought it sounded reasonable, live and learn, worked their for a dozen years until the recession so i was forgiven I guess.
About that long ago a Canadian commercial airliner requested fuel in kgs. and received it in lbs. the number was entered in the flight computer as kgs. They flamed out a few hundred miles short of their destination. By luck only they successfully glided onto the runway of a decommissioned Air Force base that was being used for automobile racing. Someone saw the airliner on approach and the cars were able to clear the runway.
Ah, the Gimli Glider. Still everybody’s favourite cautionary tale.
Thank you I could not remember the book title. Wow! 34 years ago. How time flies by (pun intended).
In addition to lbs/kg and inch/cm, there are a number of other units of measure that are foreign to us here. Last year I hired a mechanic who had spent 8 years at a VW/Audi only shop. We were talking about a fuel supply issue on a car and he told me the fuel pressure was running about 3 bar. I said “Bar? That’s where I stop on the way home. What’s it in psi?”
He also has a torque wrench that reads Nm.
Every time I grab the shop scan tool after he uses it I have to change the settings back to English because I don’t want to read pressure in kPa or temp in C.
I once owned a metric crescent wrench marked 200mm. Otherwise known as 8 inch.
When I was at the Benz dealer, one of the shop foremen there didn’t want to play the metric game
When somebody approached him about a low compression engine that was still under warranty, he wanted to know compression in psi.
As far as I know, he submitted all warranty documentation in non-metric measurements, and I don’t believe he ever got into any trouble because of it. No claims were denied because of that. Sometimes for other reasons, but not because of the measurements.
he said since we’re in America, we’ll use psi and foot-pounds, that was his philosophy.
my digital inflator gauge can display pressure psi, kpa, and one other one
my digital torque wrenches can also display in ft-lbs, nm, etc.
No problems, either way