Ovinomancer
No flips for you!
Sigh. It's not 6-8 encounters, it's the daily adventuring XP budget. Swap up to all hard, and it's like 4-5. Swap in a deadly, and it's 4 or fewer.They are impractical because 6-8 encounters do not fit in the average session & trying to cram that much combat in across multiple sessions results in losing track of any plot & things going on when 2-3 sessions of combat wrap up. There is also the body count problem where you wind up with things like 200% of a town's population being part of the evil cult in town.
Yes you can make changes that sorta fix the bad baseline, but that runs into trouble with making it more difficult to make changes elsewhere without a lot of changes. At the end of the day the 6-8 encounter expectation so many things are tuned to is a bonkers mistake that should never have happened even if >70% of the mostly players surveyed said they want to see much longer adventuring days with more combats than their gm gives them.
With this in mind, you can make some very small changes to how you present encounters and easily get here. Want to burn deadly XP but not be deadly? Great, link 2 medium encounters (or 1 medium, 1 hard) so that the second is arriving as the first is finishing. Waves make for great, engaging combats that burn the XP budget but don't overwhelm, and make lots of sense that not all of the bad guys are clustered together to begin with. Simple.
Or, make a random encounter really random, with maybe just this one isolated group today but tomorrow it's the lead element in a war party, or you find a lair of monsters and it's a mini-dungeon with 3-5 "rooms". These things are very simple to implement and get you to the expected baseline easily.