I only do coolant changes in the summer. I should have mentioned that.
Most coolant manufacturers don’t recommend a mix stronger than 70/30 as freeze protection become counterproductive.
Besides always heeding what you’re talking about (the mixing and the freeze temperature), I’ve shared some other safety information about coolant (anti-freeze), either straight or diluted, on this forum over the years. It becomes dangerous to handle in very cold weather.
I store all my coolant in my unheated garage. Once, I was topping off coolant in one my cars at an outside temperature between zero degrees F and 32 degrees F and dribbled some on my bare fingers. The flesh turned white, immediately, instant frostbite! Liquid cools much faster than air. People can survive a long time in 60 degree air, but not so much submerged in 60 degree water.
Also, where salt is applied to snow and ice to melt it, people with pets don’t often realize when walking animals through that slush and liquid salt-water at temperatures below freezing, that pets can freeze their paws, painfully.