Im not saying its a shab product, all I am saying is that there is a downside to how it works.
A 'fill line' is a small ledge of lifting that comes about from either nipping, or not evenly blending out lift.
'Line remover' type of products are essentially cyanoacrylates (i.e. tip adhesives) resins that 'run' under that little ledge that was not removed correctly in the first place.
This floods that area, making it translucent and BAM... no more line is visible. SO yes... it does work.
However... that area that you dumped a bunch of adhesive down was not sanitized. Yup... you can not effectively remove oil, moisture, or reduce pathogens in that area... so what happens? What happens when you stick product, or tip adhesive to an area that is not properly prepared?
Heres another thing:
Cyanoacrylates are simple polymers... (single linked) and are substantially weaker pound for pound than cross linked (or even reinforced cross linking) systems.
A nail enhancement that has had line removers applied throughout the lifetime of the service will be a nail enhancemnt that is essentially 'glued' on, with countless 'lines' of cyanoacrylate resin running through it. Therefore, it is bound to be less strong.
Also, since the adhesive is being applied to unprepped areas, it is far more likely to 'pull away' from the nail and promote bacterial infections.
This is not a slight on NSI's product or people... They have good products and good people. This is simply my experience with clients that have had line removers applied in the past. IMO the most effective way to remove lines during a rebalance is to buff up to them... not cover them.
Hope this helps explain my reasoning