You're not supposed to preserve it.
You're not supposed to rely on it.
You're not supposed to build your game around having in on field.
You're supposed to call it in as either, last resort to try to make a comeback or to make that final push that'll secure the game for you.
If you want to preserve and rely on tiger for your regular, normal build order, you're supposed to pick normal tiger from half a dozen doctrines its in.
I know what it's for, I just think the concept's daft.
It's never been a mechanic that fits well into the game. It started out as an 800 MP GG button, and it's been progressively scaled back from that. The idea of a cheap call-in ubertank that turns your income off just doesn't work well in practice. In my opinion they should either rework it into a normal unit, or put the resource malus on a timer like CoH 1.