Sidi lasts long because it plays a scenario with attack and counterattack and therefore both sides bleed if played out nicely.
Tulagi and Philippines have a very slow bleed and lots of chances of stalemate, both things which could be reworked in a future update.
Now when I think more of Sidi it's not just the time it takes to play out, but also the distances between flags feel very long.
Yes precisely, they're most of the time on a stalemate situation and even when the other team has bleed it's still way too slow. May be better in a campaign but in public play not so much.
What's bad about a long match? The longer the match, the higher your score can be.
It's bad if it's a map you dislike