I use the healing rules Mike tweeted about for years :
Each PC heal his level worth of hp + his con modifier (with a minimum of 1) after each long rest.
So a 1st lvl character with 14 hp et 10 con (+0) will heal 1 hp/day (2 weeks to fully recover from being down)
A 1st lvl character with 20 hp and 17 con (+3) will heal 4 hp/day (5 days to fully heal back)
High con PC will heal faster but it still take days.
A level 10 fighter with 85 hp and 17 con (+3) will heal 13 hp/day (6-7 days to fully heal back).
While it doesn't perfectly scale, this rule still work fairly well at higher levels, even though high lvl PC don't typically use natural healing anyway.
It's not perfect but it's a good compromise between "instaheal bruise/luck/exhaustion overnight" and very long realistic healing.
(sorry for my english, not my 1st language)
Each PC heal his level worth of hp + his con modifier (with a minimum of 1) after each long rest.
So a 1st lvl character with 14 hp et 10 con (+0) will heal 1 hp/day (2 weeks to fully recover from being down)
A 1st lvl character with 20 hp and 17 con (+3) will heal 4 hp/day (5 days to fully heal back)
High con PC will heal faster but it still take days.
A level 10 fighter with 85 hp and 17 con (+3) will heal 13 hp/day (6-7 days to fully heal back).
While it doesn't perfectly scale, this rule still work fairly well at higher levels, even though high lvl PC don't typically use natural healing anyway.
It's not perfect but it's a good compromise between "instaheal bruise/luck/exhaustion overnight" and very long realistic healing.
(sorry for my english, not my 1st language)