I find the myth of 6-8 being "needed" to be mostly not needed. It's there not as a recommendation but as a measuring stick, after all.
My games tend to run a mix, sometimes its 1-2 encounters between long rests, sometimes its 3-5, sometimes it's more. Tends to work fine but gives each time to shine.
The tired vs fresh balancing act is not new for 5e, not unknown for GURPS or HERO or most any RPG where uses per xxx or recovery was a thing.
Different strokes for different folks and all, but I find having a higher number of combats keeps my game more sane especially at mid-to-high level. Before I did that, it felt like he casters would just go nova every combat while the classes that didn't need to worry about resource management as much were left behind. Occasionally I broadcast that they need to pull out the big guns and will only have a couple of fights before the next long rest. I guess I'm just saying that I like having a variety of encounter "days" where sometimes resource management is critical and I want that champion fighter to shine by being slow and steady and other times when the blasters can go wild.
I use the alternate rules (a long rest is several days, usually a week) and get in plenty of RP.
I'd recommend trying both and see which works best for you and your style of play. I rarely do dungeon crawls, and many campaigns span years if not decades so the alternate rule pacing just fits my style better.