Maintenance schedules are there for a reason. And that reason is to verify that everything is working as it should. "Better safe than sorry" is the old adage.

It will be mandatory on some bikes and useless on others. Unless you do the checking, you'll never know. The problem is there is no way to classify this based on what others get. It totally depends on how the bike is ridden, how it's maintained in other areas, and what the starting point was. They set a catch-all value against the maintenance schedule to cover everyone.
It's not one of those things that you should stop riding for and rush out to do. It's also not one of those things that should be neglected for another 5k miles or more. Look at your calendar to find some free time, make an appointment in the future that fits that, and just get it done when that fits in.
It will likely take a shop the better part of a day to do it. Most of that time is stripping the bike. You can shorten that by stripping down the bike yourself and taking it to them ready to check. Otherwise it's likely to be a $5-600 or more job (depending on what they charge for shop rates) and what else they find. Strip it down yourself and you can cut half the cost of that off if you talk to the shop about it and they'll work with you.