Tank APS last 3s and does not even prevent first shot

It makes no sense to have both a 3s life and not preventing the first short.

Ideally first short should be blocked and it should last 7-10s.

Lets say 3s is intentional, then first shot should be blocked.

If not, and the intention is that you deploy APS before going into a hot zone, then it should last 7-10s.