Is it necessary to go to the bare metal, use a etching primer and then the Evercoat body filler?

I have received conflicting information from several sources and wanted to run this by the good members of moparts.

I have heard that evercoat can only go over bare metal, and have also heard it can go over sanded/prepped primer/paint.

I have glazing putty for the final filler.

Thanks in advance!