Picture a typical situation, 15 m² of existing vinyl tiles on dry concrete to be replaced with a vinyl design floor. The specification says, remove old floor-coverings, remove any loosened old smoothing compounds, remove old adhesive residues, prime the surface and allow to dry, apply 3 mm of smoothing screed, allow to dry fully, rub down imperfections, install new tiles. Sometimes it can be difficult to get as far as laying the screed in one day!
OK so you hope you’ll get away with it if some, or even most, of those get missed out, to save time. But you cannot lay tiles before the screed has set, so you either wait a few hours, hoping it sets quickly enough, or return the next day.
All rather risky and unpredictable!

Alternatively you could use Jumpax. You can safely leave the old tiles down, then lay out polythene, lay Jumpax, lightly sand the joints and lay new tiles immediately. No waiting, no uncertainty, no return visit, NO RISKS.