You are spot on with your 1% statement (which could be as little as half that, due to rounding). The percentage used is base on the figures set by the manufacturer. It is the one used in drive warranties. Also - worth pointing out that it doesnt mean the drives stop taking writes at 100%. This counter actually goes up to 255 (per spec), where 255 means 255+. Its literally just for life "expectancy".
Some people saying to ignore that and to look at TBW. They simply dont know what they are talking about! No discussion around the nand type on these drives. Is it SLC, MLC, TLC, QLC? or is it one if the hybrid modes, such as pSLC, or iTLC which act like the higher categories? This can mean the difference between <1k and >100k+ P/E cycles.
We simply dont know what the OS is doing. I know that I can have WAY more applications open (and remaining responsive) on my 8GB M1, than i could my 16GB i7. It doesnt feel like traditional swap - so maybe its not. Maybe its way more aggressive, suspending entire applications to disk in the background - taking advantage of the massive bandwidth to make the UX better at the cost of drive writes. We simply dont know.
From following the original thread, the vast majority of people reporting 1% usage since launch. There are a handful with higher usage than that. We dont know what these people are doing on those machines, but its evident from the figures that that the writes generally scale to the amount of ram on the machine. 8GB machines generally seem to be a lot less usage than 16GB. Maybe these people with HUGE amounts of writes are running a memory hog like chrome, which consumes all available ram on the machine, and which is paging when they background it. Some people reporting 8hr daily usage since launch with 200 drive power on hours (drive hours arent same as uptime, as drives can be suspended for power saving), others reporting 800 for same "uptime". Clearly it is due to the workload.
EITHER WAY, the "percentage used" is definitely the figure to go on, because only the manufacturer knows exactly what NAND types they are using (unless someone wants to enlighten us?) as well as the wear levelling algorithms on the controller.