Mine has been on 81% for over 12 months now. It could be anywhere from 1-24 months for it to drop to 80%. By the time it reaches 79% and qualifies my AppleCare will long be expired. I have a 14” M1 Max too and over 500 charge cycles.
I've had my MBP 14 Max now since 2021 now - I'm eyeing up a M4 Pro upgrade - the prices for the M4 Max's here in Japan are scandalously expensive.
I was just worried it was suddenly gonna drop below 80% and give a service recommended warning at point of trade in. Basically batter service recommended = huge drop in trade in value.
Yes, agree with others, could be awhile. I think most of us thought you'd prefer it the other way (ie. go below 80% faster, so you can use AppleCare or battery-replacement-price to get a new one from Apple). That's usually the way these threads go! (Not just for MacBooks, but especially for iPads, where Apple is very strict on the <80% threshold to get battery replacement price, as they generally just give you a whole new refurb iPad).
As @okkibs said, if you're trading in directly from Apple, it shouldn't affect the trade-in price. (Assuming Apple Japan is the same as Apple in the US). However if you're selling on another secondary market, then yes, I imagine the market value decrease if you're <80% / have the battery service recommended price.
Mine hung around 80% for a while and then dropped to 78% and I have just had it replaced as this computer is fine with lots of RAM and storage and a MAX chip. Can definitely see the difference and the new keyboard is nice too although unexpected.