I'd suggest worrying less about individual squares, and always err on the side of what's more interesting.
'Is he close enough to the fireplace I can push him into it?' = The answer should almost always be 'Yes'
Consider the battle in sorta short conceptual zones, rather than individual squares. 'I jump over the pews and get onto the dais near the altar'
Some short hand for handling ranged types trying to avoid OAs I'd probably use - engaged and pinned. If a melee guy is in the same zone, he can choose to engage other people in the zone, and a 1-square shift lets you disengage from one guy. If you're engaged in such a way that you can't shift out (like in a corner, blocked by a table, etc) then I'd say you were pinned in. That way you know when to use multi-square shifts and/or just provoke when moving.
In general, I wouldn't sweat the differences between push 2 or 3... a push 1 is near, maybe disengage someone, pop them into something interesting in the zone, _maybe_ move them into a different zone, a 2-3 definitely can put them in a different zone, a 5+ sends him almost anywhere. In general, interesting and fun trumps worrying about any math.