I like to maximize my units, even if the costs/time don't worth... My Kubaz is level 5, but I'm okay with that. I unlocked the T5 recently and I'm keeping it at level 4 after reading this post, but never really used.
If you want to save your troops, you should maximize your T5, and maybe you can get the 3 stars. While I'm only attacking for the loot, i don't care, I will sacrifice every troop if is possible to destroy a full storage building. Then I prefer to use the space for 1 or 2 Strikers to kill enemy troops in the way. And if the troops can't reach the last storage buildings, 1 or 2 Tie Brute will do.
A Windows survivor now training players and helping squads through the Galaxy!
Imperial HQ10 in "BombSquad18" (Level 49 squad)
Rebel HQ10 / HQ8 in "Ewok_revenge" (Level 50 squad)