No need to worry about thin, thick etc. the dual form takes care of it all for you! I know it seems unbelievable but your finished nail will have the perfect FORM, APEX and SHINE (with a LITTLE practice of course).
Each new client often has a different length nailplate, therefore i'd imagine the apex would have to be in a different place for different peeps.
If the poppit/form/mold has a consistant apex in the same place, lets say 4mm along the form/mold, how can the apex be moved to suit different clients?
If it's a matter of angle of application of the poppit, on a short nailplate, would this mean angling the poppit upward? (is this just my perception of how they work).
Perhaps while creating the apex in the right place with angling to adjust apex placement, this may also give the nails a bit of a skijump appearance.
As with any method, I like to see demonstrations on a variety of "typical" clients.