yes I do 
For what reason? 1-2 more rounds will knock out anything short of a tiger, and 1 more round from a Panther, Firefly, or Tiger would probably knock out anything short of a Tiger II. If you've already acquired the range, your next round should hit if you're in a german or soviet tank (which also means your next round should either kill him, or knock out his turret/engine), and if you're in an M4, maybe 2-3 rounds untill you have the range.
Guess how long that takes? About 10-15 seconds, or roughly half of your suggested time. A tiger II could get 3 rounds down range in 30 seconds, and those things are almost guaranteed one-hit-kills. I shouldn't be able to kill you 3 times over before you can move again. And besides that, just killing you once will do, I don't need to fire 3 kill's worth of ammunition.
And honestly, if you feel like you need another 30 seconds of fire-correction before you get another hit... you probably only hit him by accident the first time.
But what I think is really going on here is that you have 30 seconds stuck in your head because of the rearm pad. If the rearm pad were set to 45 seconds, my bet is you'd say GV's should sit still for 45 seconds, and for a minute if the rearm pad took a minute.
You'd probably say you just thought that happened to be a fair time, and that its just coincidence. You'd probably even think you were telling the truth, to.
By the way, I'm dead serious about sitting for 30 seconds before you take supplys. Time yourself, and tell me what you think is a fair amount of time (from your perspective).