Shtora is really not an APS. It's more of a countermeasure system designed to fool the laser guidance used by missiles etc. Think of it like ECM for a tank.

APS is more along the lines of Trophy (Israeli and eventually US), or Drozd/Arena (RU) where radar senses projectiles, and fires counter projectiles at the incoming round/missile.

Drozd was never really implemented; partially due to cost, but also because it tended to kill any infantry accompanying the tanks. Arena appears to be much of the same tech, focused on RPG type weapons as well as ATGMs. I think the reason we don't see much of it on the Russian tanks is again, cost. The export version was pitched to South Korea at $300k per unit. And compared to the cost of a T-72B3, that's a significant amount to add. Or it could be the typical Russian military corruption we've been seeing in Ukraine.

I think you are confusing APS systems in general (of which Shtora is one) and the subset of APS systems that are hard-kill such as Trophy.

Of course regardless of efficiency, an APS system has to be installed in the first place and it is possible that that is not the common case in Ukraine.

APS generally refers to hard-kill systems like Trophy/Arena. Things that actively go kill the missile or projectile coming towards the fighting vehicle. Shtora is not active, it simply disrupts the laser guidance (if it can detect the beam in time). It's no different than an ECM jammer on a fighter or surface ship.