Sorry probably didn't make myself clear. Where the older lashes have grown out slightly ( ie 2mm) then they can drop slightly so you get the brand new lashes that are applied 1mm away from lash line sitting at one height and the older lashes sitting slightly lower so you then have a set of lashes that do not sit uniformed x
Is it possible you are using lashes that are a little bit too heavy for the natural lash?
In answer to your original question, I never use remover at infill time. I don't really have to remove many lashes at infill and if any have become detached a bit I just use both sets of tweezers to peel the lash off.
I think they tend to look messy or twist if lashes are too heavy, too long, or not properly attached at the base.
I also think infilling with shorter lashes helps to form a good foundation for the longer lashes and helps keep them in place IYKWIM?
I would say 80% of my lash clients are infills. I fill for 45 minutes and their sets look brand new.