Is my nail prep the reason gels are lifting?

Hi geeks, i wondered if someone could provide me with a solution... Recently I've had clients coming back saying their gel has peeled after only a few days, it only happens with a few of my clients and others can go for ages with the gel that i apply. I was perhaps wondering if I'm doing something wrong whilst prepping their nails? or perhaps the layers are to thick? should the base coat be thinly applied and would this be an issue if it wasn't?
Anyway, here are the stages of my prep...

Is my nail prep the reason gels are lifting?