Putting car in neutral

while at a lengthy red light. I have a 2002 Camry and have been doing this for a year now and wonder if there is any harm, or good, done by doing this

If the car has a manual transmission, shifting into neutral and releasing the clutch is a good idea if the car is sitting still for any length of time.

If it has an automatic, you should leave the transmission in gear at traffic lights. You’re not helping anything, and you could be causing additional wear with the extra shifting on an automatic transmission. It doesn’t save any gas shifting to neutral.

When you shift an automatic transmission from neutral into gear, the whole drivetrain takes a jolt. Although the drivetrain is designed to withstand this jolt repeatedly for many years, doing this more than necessary will accelerate wear and lead to premature failure. So if your car has an automatic transmission, stop doing this and just leave it in gear at red lights, no matter how long they last.

Except for manuals, it makes no sense.

Neither harm or good as long as everything else is operating normally. The real question is does it make you happier to feel like you’re prolonging the life of your transmission by taking it out of gear? If so, by all means continue to do that. Since it is a Camry, I’ll take a guess and suggest it has an automatic? With either trans, it doesn’t make any difference. After you take one apart and see how they operate, it makes it easier to understand how they can sit at idle and not cause any wear and tear, even though the car will creep forward when you remove your foot from the brake pedal.
As Abe Lincoln said: “Most folks are about as happy as they make up their minds to be.” Don’t worry. Be happy.

Here’s my problem - you forget once to put it in drive, light turns green, you hit the gas, nothing happens, slap it in drive, WHAM - very bad for the transmission.

If you are doing this to save gasoline, you may be fooling yourself. It is quite possible that the vehicle is programmed to burn more fuel in neutral than in drive. Idling in neutral would be considered to be a very temporary condition. Idling in neutral or park might require more long-term considerations for fuel air mixture and the proper function of the cats.