I've been working on the mechanics for combat, and I noticed something that you pointed out: a single player acting on consecutive turns really unbalances things. Thanks for your insight.
Another thing I've noticed: overtaking a square may work for chess, but not for skirmish-type combat; it may force you into a pincer. If a character wanted to defend a narrow area against multiple opponents, he wouldn't be able to take advantage of the bottleneck effect.