Here is the exact wording from the Yamaha rigging guide for an F150, and that is the way we do it as well and have never had an issue.
7. Install the mounting bolts, and then
tighten the nuts firmly.
Make sure that the clamp brackets do not
bite into the boat transom.
8. Tighten the locknuts firmly.
One thing to remember is you always want to put a wrench on your bolts from time to time to make sure they do not get loose. Lots of times over time transom’s can compress a little and the bolts will loosen up. Or if they get water in the transom’s and start to get soft they will really get loose.