How often do floor drains need attention?

Floor drains seem easy to overlook until there’s an odor or water starts draining slowly. What’s a sensible routine for keeping them clear and preventing trap odors without damaging the drain or nearby finishes?

I’m especially curious which types of floor drains need water added periodically to keep the trap from drying out, and whether safe cleaning methods differ by drain or trap design. If an odor or slow drainage shows up, what signs help distinguish routine maintenance from a blockage or venting issue that needs a plumber?