> don't expect them to make suggestions for a year

That's not the problem.

The problem is that some newbies want all of the code to be their design pattern of choice; or just want to refactor things until they understand it. Some will just refuse to follow established design patterns and do things like bypass our dependency injector.

For me, it's a red flag whenever someone comes on a team and immediately wants to refactor to use their favorite design patterns, frameworks or style. It's not that their preferred design patterns are better or worse than what we're using; it's that you just don't refactor code on a say-so.