The issue is that '6-8 encounters a day' generally means a dungeon bash. Now I love a good dungeon bash. But particularly as you get to higher levels lots of sessions feature other things, like travel, diplomacy, mystery solving, and so on. So a lot of adventuring days might only feature one or two fights, but they are likely to be bigger ones with large groups of enemies or important plot points. The battle of attrition that 5e is balanced against doesn't come up and play more closely resembles a fantasy novel or movie.
Our last adventuring day featured two encounters (we're at level 16 travelling through the Cairn Hills)
Our last adventuring day featured two encounters (we're at level 16 travelling through the Cairn Hills)
- A battle against 25 sword wraiths, which was won by the casters spamming area effect spells and turn effects. My fighter did use a wand of lightning bolts to do some damage but I didn't get into melee at all - by the time they were close enough there were so few left that the casters could mop them up with cantrips and there was no benefit to me providing them with a melee target.
- An ambush from a house by a bunch of crossbow-wielding hobgoblins and two ettins. My fighter get into melee against the ettins, but a lot more damage was done by firestorms, blade barriers, and so on from the casters.