If nothing else, it's a good idea to break the bolts and retighten them from time to time. Mostly to make sure they haven't worked loose or are starting to rust solid. Maybe not all of the bolts, but definitely the ones that would see some regular use through routine maintenance. The last thing you want is to need to replace the blade, only to find out the bolt won't come loose, and it becomes a huge hassle just to replace the blade.