depends on what you feed it.
rotovaps remove solvent.
they don’t “make crude”.
how much cannabis you can get into a gal of solvent determines how much crude you get when you remove the solvent. that depends on the temperature you extract at. at -40C you can get at least 3lb into a gal if you know what you’re doing. at rm temp you might be able to get 10lb in there.
what are your plans?
do you have a centrifuge?
it’s getting quite long in the tooth at this point, but if you haven’t already read the Ethanol Extraction White Paper I’d start there.
the chiller that came with your rotovap also makes a huge difference in how fast you can run it. if you purchased a “turn key” system, chances are your vac pump AND chiller are under powered.
maybe check Optimizing your RotoVap