There's a feature - when a merc stands in overwatch and shoots - he also knees after a shot. One point to knee. And it's automatic - I can't stop him from kneeing. There happens that the merc has enough points to shoot twice, but doesn't - he knees and the point is lost. It'd be nice to have a way to use this or not.

That's because it's better to kneel behind cover rather than staying standing and exposing the soldier to enemy fire.

You can deselect the auto-overwatch feature in settings and then you have control of what the soldier does in overwatch mode.