Went from 8 to 6 to current format
Yes, and when it went back down to 6, the number of inter-conference games was increased back to almost reach the point of every team in every building every year. Then, the realignment to 4 divisions reduced the number of division games to 5 or 4, and eventually 4 or 3 once expansion happened.
Here's another interesting thought experiment: since it's actually not necessary to align the league into conferences / divisions that all have an equal number of teams or is divisible by 4 or 8 (just need to adjust number of games and follow a playoff format that allows equal odds of making them),
what if the NHL kept its 6 division format, but shook up the alignment of said 6 divisions?
I'd say you would have had the following:
Pre-VGK expansion:
Northwest: VAN, CGY, EDM, WPG, MIN (not ideal at all for VAN/WPG/MIN, but better than MIN being the only Central team)
Pacific: SJS, ANA, LAK, ARZ, COL
Central: CHI, CBJ, STL, DAL, NSH (DET gets priority to move East, knowing CBJ will follow in a few years)
Northeast: BOS, BUF, MTL, OTT, TOR
Atlantic: NJD, NYI, NYR, PHI, PIT
Metro: DET, WSH, TBL, FLA, CAR (DET here only because no team from any of the other 2 divisions can be split off yet - adds an original 6 rival to the Southeast Division, which was badly needed)
Post-VGK expansion:
Northwest: VAN, CGY, EDM, COL, WPG
Pacific: SJS, ANA, LAK, ARZ, VGK
Central: CHI, STL, DAL, NSH, MIN
Northeast: BOS, MTL, CAR, TBL, FLA (not ideal to split TOR/OTT from MTL/BOS, but flex schedule might be possible to bump up the games)
Atlantic: NJD, NYI, NYR, PHI, PIT, WSH
Metro: TOR, DET, BUF, OTT, CBJ
Post-SEA expansion:
Northwest: VAN, SEA, CGY, EDM, COL (boom - American rival for COL, all Mountain teams together for TV start time optimization)
Pacific: SJS, ANA, LAK, ARZ, VGK (boom - ARZ keeps all of its natural rivals)
Central: CHI, STL, DAL, NSH, MIN, WPG (boom - one 6 team division means all 6 Central teams can be together)
Northeast: BOS, MTL, CAR, TBL, FLA
Atlantic: NJD, NYI, NYR, PHI, PIT, WSH
Metro: TOR, DET, BUF, OTT, CBJ
This would be quite optimal, I think, other than the old Northeast being split, but depending on the schedule and playoff format, they could still see plenty of action vs one another. For example:
5-team Divisions: 5 games vs. 4 division rivals (20 games) + 3 games vs. 5-team division (15) + 3 games vs 6-team division (18) = 53 games + 29 non-conference games (so, home and home vs. all but 3 teams, rotates every year) or pare this down to 27 non-conference games to pair up whole divisions for 1 game on a rotating basis and add 2 intra-conference games for flex scheduling (i.e. MTL/TOR, CBJ/PIT, COL/MIN, WPG/CGY, etc get 4 games instead of 3)
6-team Divisions: 4 games vs. 5 division rivals (20 games) + 3 vs. the 2 5-team divisions (30) = 50 games + 32 non-conference games (so, the 6-team divisions can play home and homes vs. all the non-conference opponents, while the 20 teams from the 4 5-team divisions would only pair up against each other for seasons to play only 1 game on a rotating basis).
Then the playoff format could be a hybrid Conference/Division format. I'm thinking the old 1-8 Conference-based format, but either (i) the 3 Division winners get the top 4 seeds in order of record along with the top 2nd place team, rather than each of the top 3 seeds, or (ii) the top 2 teams in each of the 3 Divisions get auto-clinched playoff spots + next 2 teams by record, and are seeded entirely by record (so the 1st/2nd place teams can be seeded 6/7/8 if that's where they are in the standings).
Example of this using last year's playoffs (not the right schedule format, but use your imagination):
West:
(1)VGK* v. (8) WPG, (2) EDM* v. (7) SEA, (3) COL* v. (6) MIN*, (4) DAL* v. (5) LAK*
East:
(1) BOS* v. (8) BUF*, (2) CAR* v. (7) NYI, (3) NJD* v. (6) TBL, (4) TOR* v. (5) NYR*
*Top-2 in Division
So, in this example, it doesn't really affect seeding or which teams earn playoff spots, except for BUF making it over FLA because they are 2nd in their Division, while FLA is 4th.
Would be pretty interesting, and there are obviously alternatives to what I've laid out here for a 6-division format. Seems really, really good for the West at the very least, which is worth considering...