Twice a year drain checks
Roof drains and scuppers should be checked and cleared at least twice a year, once in spring after seed pods and pollen buildup, and again in late autumn once leaves have finished falling. A drain blocked even partially causes water to back up and pond, and standing water is the single biggest accelerant of every other kind of flat roof failure, from seam degradation to membrane blistering.
For buildings with several roof drains, keeping a simple record of which drains were cleared and when makes it easy to spot a recurring blockage pattern rather than treating each visit as a fresh problem.
Watching the seams
Membrane seams are the most likely failure point on any flat roof, more than the field of the membrane itself. A visual check from the roof surface every few months, looking for lifted edges, cracking at seam tape or heat welded joints, catches most problems while they are still a small and inexpensive fix rather than an active leak into the ceiling below.
Recoating on a schedule
A reflective coating applied to an intact membrane before it starts showing widespread wear can extend a roof's useful life by several years and helps with cooling costs in the units directly below the roof deck during summer. Waiting until the membrane already shows extensive cracking usually means the coating window has passed and full replacement is the more honest recommendation at that point.
After a major storm
Following any significant wind or rain event, a quick check of the parapet flashing and any rooftop equipment curbs is worth doing even if nothing has leaked yet. Flashing that has started to lift is far easier and cheaper to reseat before it fails completely and lets water track down inside the wall.
Keeping a simple maintenance record
A short written log, even just the date of each drain check and any repair made, becomes genuinely useful over a few years, since it shows whether a particular drain keeps clogging in the same spot or whether a seam repair from two years ago is holding up. That record also helps whoever inspects the roof next understand its history rather than starting from nothing.