How it's done varies by state. You have to be careful in most states lest you get caught being overly flexible with the rules:
From Peter Grants page.
In Colorado the rule is that you're allowed to deposit up to 10 ballots at a time into the drop boxes, then you have to go back to your car for the next 10. Please remove the rubber band from the bundle before depositing. Finding 20-30 rubber banded bundles in a drop box raises eyebrows when they are counted as the signatures seem to be all in the same handwriting.