Interim cleanings for me (Kanger T2, CE4 varieties) occur when a few tankfuls have left me with a small amount of darker residue at the end of a tank. This involves removing the head, rinsing tank and head in hot tap water, patting wicks dry and blowing all liquid out of both. It takes about a minute and goes right back to work. Thorough cleaning, involving dry burning and flavor wick replacement, occurs every week or two and takes about 10 minutes.
This reminds me how much better vaping maintenance is compared to cartos a couple years ago, with frequent topping off, repeated flushings, hole alignment and taryn spins. And they still never tasted very good after the first fill.