The swivel quick-disconnect handpiece has been around for decades. This ingenious device not only allows rapidly changing out handpieces but helps reduce wrist fatigue and improve access. But, just like your handpieces, the couplers need maintenance too.
Perhaps the most important thing to remember is to remove the swivels from your hoses at least once a week. Over time, the threaded connection between the coupler and your hose can corrode from disinfectants or other environmental factors. Depending on the specific make of swivel and threaded hose coupler, galvanic reactions can also occur. Whether from a galvanic reaction or simple corrosion, having a swivel "locked" to your hose can be troublesome at least and potentially ruin both it and the threaded hose connector.
Before the CDC "Summary" was introduced requiring sterilization of slow speed motors after each patient (https://www.cdc.gov/oralhealth/infectioncontrol/pdf/safe-care2.pdf), slow speeds were often left on the tubing for months or even years at a time. It was not unusual to encounter slow speeds "locked" on the tubing. Don't let this happen to your swivels. By simply removing them from the tubing at least once a week, you can assure the threaded connections maintain function.
Of course, while not in direct patient contact nor introduced into the oral cavity, it's a good idea to sterilize your swivels periodically as well. Most are designed to be fully autoclavable.
If you don't want it to be a permanent attachment, remove it now and again.