I depends what marker you're running generally.
I tend to do a light service - clean, take apart bolt system and relube - after every training session and then maybe do the same with hpr / lpr every other month or just a time when I had time.
In my experience with eclipse and dye markers, the more 'complicated' components are ok to be left for a few months unless something goes wrong, apart from a service or even just a look to check over everything is in order.
- As for doing too much: If you're inexperienced or not exactly sure what's going on, a service can easily act in creating more problems. As long as you know everything is in general order "If it ain't broken, don't fix it".