Mike,
It depends on how long it will be before you paint the whole truck. It is OK to leave primer, but if it is going to be a while before you paint the whole truck, you should follow up with a primer-sealant.
If you do a second-rate paint job on each panel, you'll increase the amount of prep work you'll have to do before the final paint job, and re-prime.
That's what I was taught, anyway . . .
Good luck,
K
