I haven't sewn in 3 years now.
If I recall correctly I cleaned the overlocker during and after if I was sewing fleece or cotton knit. Since I sew sporadically at best I always take a quick look inside before I start sewing. The sewing machine gets cleaned out every time a bobbin comes out for color change or to refill. Takes less than one minute.
BTW, I change the needle at the beginning of any significant project, a new quilt, or if the last project was polyester. If I'm sewing pillowcases I can sew quite a few. A dull or dulling needle makes a different sound when it pierces the fabric.