Have you actually run a game and experienced balance issues from not running 6-8 encounters?
I have plenty of times. After DMing AD&D 1E/2E for the last 30 years the idea of a 6-8 encounter work day was just not part of my thought process. 6-8 encounters per day exists because of the giant action economy that the players have.
If you either don't throw enough encounters at your players to use up their action economy OR you allow them to rest easily then the game truly becomes easy mode. Once you aren't going to easily run out of abilities then the nova problem occurs.
The problem I have with this design philosophy is that 6-8 encounters per game day @ 10-60 minutes per encounter in real time means game sessions just become hack and slash. I prefer less encounters and more roleplay, that means I have to push my lower number of encounters more into the deadly range to use up their actions without them just blowing away all the encounters. The other option is to make changes to healing, rest, and how easily they get their abilities back.
If your players enjoy 6-8 easy-medium encounters per long rest then more power to them.