There is a discussion of the timeline of all Might & Magic and HoMM titles:
https://www.celestialheavens.com/forum/10/11591

Yes, all the campaigns, except maybe HoMM 1. I don't remember if it had difficulty settings.

The HoMM games are definitely more enjoyable if you start with no resources, unless it's a map (usually Small) where the enemy turns up and eliminates you before you have built even a Town Hall.

I even replayed the Heroes Chronicles using only auto-combat and always choosing the worst skills (like Eagle Eye over Earth Magic) to "prove" how ridiculously easy they are. It was only when I reached the seventh of the eight (Revolt of the Beastmasters, I think) that it became too difficult with these handicaps.

Playing in release order is much better than the above. Especially for first timers.

LOL! never played auto combat. i care too much for my troops :D

That's an interesting comment as I always automatically assumed everyone agreed HoMM 3 had the best campaigns.

I only ever played HoMM 2, which I got back to recently and just today I finished the Roland campaign (for the first time ever! didn't go far as a teenager) and holy shit that last scenario - it took me way over 20 hours to finish!! (obviously several sittings) The penultimate mission was the 2nd longest at 9 hours and third longest was that Sorceress' Guild scenario at 7 hours. Besides those, the average mission took 4-5 hours.
Just... damn!
And to be clear: I never thought it was extremely hard, at most both the Sorceress' Guild mission and the finale I'd rate as definitely above average difficulty and probably frankly hard (had to reload a save several times throughout), but the main thing is that the nature of the game makes everything so slow, definitely not my preferred type of pacing.
And well you know, the narrative isn't really anything to write home about (main plot is average, world-building is good, so overall the narrative experience - combination of implicit and explicit narrative - is just about above average, 6/10).
I figured from the reviews and such that HoMM 3 would be an improvement across the board.

I am sort of hesitant to start the HoMM 2: Price of Loyalty expansion campaigns now as I remember reading somewhere that it gets tougher than the Succession Wars campaigns, and I don't think I like the game enough to spend, on average, something close to the equivalent of a day's work on each mission.

wow. those are crazy numbers. i ended up starting with Homm3. will come back to Homm2 later on.

I think a blitzkrieg is the best way to complete most of the campaign maps, especially in the expansions.
There are several advantages to this:
1. You get a better score the fewer game days you use.
2. By not developing über heroes the maps will be more challenging and fun. To me nothing makes a game more boring than if it's too easy.
3. You waste less of the most valuable commodity in the universe: time.

I agree, and it is notable that in Armageddon's Blade at least, the issues I mentioned are lessened somewhat. I haven't gotten around to Shadow of Death yet so cannot comment on that. The thing is, when playing the campaigns for the first time, you don't know that you don't need all the stats and levels ahead of time. Naturally you can get things done faster on a replay.

But there are still numerous scenarios where you are forced to wait at the start, and I always chafe against that.

Indeed, time is the most valuable commodity in the universe :)

Not sure HoMM 2's Roland campaign always respected my time but it's good enough for one playthrough. I am itching to get back to RTS however :P

That said, I bit the bullet and decided to do the Price of Loyalty campaign - I don't know if I'll bother with the others (no sophisticated storytelling to draw you in, either) but the one that gave its name to the expansion is fairly diverse by HoMM 2 standards so I'm satisfied...