Full analysis
She provides a Skill Cooldown reduction when she's reloading, for herself and her SG partners. A shorter Skill cooldown means the other SG can activate sooner. However, it not only has a restriction that both SGs must be on the same column (which means neither of them can be kited) but also is not enough to justify fielding another her when other SGs, like M500 Mod and LTLX, which have better stats and kits, can be fielded instead.