Empty space is good for wear-leveling but enforcing a few percent extra helps.

> And most importantly 10% of the drive in ~2010 were 6-12GB, nowadays it's 50-100GB at least.

Back then you were paying about $2 per gigabyte. Right now SSDs are 1/15th as expensive. If we use the prices from last year they're 1/30th, and if we also factor in inflation it's around 1/50th.

So while I would say to use a lower percentage as space increases, 50-100GB is no problem at all.

> but enforcing a few percent extra helps.

Only if you fill the drive up to 95-99% and do this often. Otherwise it's just a cargo-cult.

> So while I would say to use a lower percentage as space increases

If your drive is over-provisioned (eg 960GB instead of 1024GB) then it's not needed. If not and you fill your drive to the full and just want to be sure then you need the size of the biggest write you would do plus some leeway, eg if you often write 20GB video files for whatever reason then 30-40GB would be more than enough. Leaving 100GB of 1TB drive is like buying a sneakers but not wearing them because they would wear.