It does not take X long to break ranks. She works best alone.

There is no need to compensate for teammates, then.

X goes for what 'high' ground she can find. Or make. Adamantium claws are useful for carving out foot- and hand-holds.

And after a little observation she will most likely launch herself straight down into a group of Combine soldiers. Unless there are too many. Then she will use her gun.