LOCA UV glue vs OCA sheets?

I run a small repair shop from home and am in the process of learning how to change the glass instead of the entire screen replacement. One thing I stumbled across is two different options for glue: liquid LOCA and OCA sheets.

How do I know which phone requires LOCA and which ones require OCA?

Also, how do I tell how much LOCA to apply for each model of phone?