Well, facehuggers only leave their eggs when a host is nearby. That aside, they stay in their eggs, which leech nurtients from the surrounding area to them.
If there was only one or two potential hosts in the area, then I could see facehuggers moving as a group as they go after those few victims. If there are several, then they might scatter and go after whoever is closest.
However, facehuggers are instinctual. They go after whoever is closest, regardless of how heavily armed or dangerous that potential host may be.
And thus I clothe my naked villainy
With old odd ends stolen forth from holy writ
And seem a saint when most I play the devil.