I'm not very clear on the effects of the Rally Flag, and a quick Google search didn't yield a lot of information.

I did find this snippet:
"Rally Flag: Improves Movement with +1 (time not specified. Checked and it's longer than a week.)

Because the hero seems to use the slowest creature speed in an army mixed with hero and creatures (Is this a bug???), this structure probably has limited use."

If the Rally Flag is permanent, then it is worth visiting (especially in a campaign) if you aren't close to the end of the map/campaign. Heroes tend to become powerful enough that they eventually strike out on their own, and the extra movement is handy.

On a small map, or if the hero always needs to have creatures along, then it becomes distinctly less useful. Also, if it only lasts a day/week, then I wouldn't bother. I've pretty much always skipped them, since I've assumed they are not permanent (I haven't tried to do any research to figure it out).

Yeah, I kind of thought they're like rally flags in HoMM3, that only give you movement for 1 day (and like the trough in HoMM 4), and the fact that they only got you +1 made them pretty much useless. But I accidentally came across the page you quoted, and if the effect is permanent, it does put them in a different light, especially in campaigns with hero carryover.

That said, I do almost always from level 2 onwards use only hero+fastest level 3 or 4 unit, so the speed of the hero himself is irrelevant.

Sure, until the hero has picked up a bunch of those Speed Crystals, and is outrunning everything except the fliers (whom he has on a string or something, like a bunch of balloons). :D

So speed crystals increase adventure map speed too? Not just combat? You learn something new every day.

...don't they? I thought they did, but I might be wrong. Been awhile since I've played this one.

And it applies to all units, not just the hero, right?

Also is it a Month from when you touch it, or just to the end of the current Month?

I always hated how in H3 outside Stables would be almost worthless unless visited early in the week.

Yep, it applies to all units in the army that touches it. Yep, one month from when you touch it (not just to the end of the current month).

Thanks, rmeakins.

This is actually incorrect, in several aspects:

1) You need to distinguish between speed, movement rate on adventure map and movement rate on battle map. Speed denotes the order in which the units act in battle and is influenced e.g. by the speed crystals. Movement rate determines how far the units can move on adventure on battle screen, respectively, and is affected e.g. by rally flag.

2) A hero actually acquires the speed of the fastest unit in his army, but the army stops as soon as any member of it loses its last movement point. If you have an army with a hero, a sprite and a dwarf and you move that army out as far as it can go and then dismiss the dwarf, you will be able to travel quite an extra distance. I generally found that giving a hero a single fast "carry" unit is the preferable course, even if it becomes necessary to separate the hero before a combat. Speed Crystals have no impact on movement points at all. 27 or less. Taking that rally flag requires at least one movement point, possibly more (depending on where it is located relative to your path). Can possibly be useful, but really it just means an increase of about 4 %, not too significant a boost overall (though it can be useful in some situations).