I think it's likely that many people use scans to 'proof' their negatives, perhaps even to the extent of avoiding making contact sheets altogether. The trick is to make a scan that you know from experience will allow you to make a similar print. Even a minimal adjustment in levels or curves is a departure from the direct link from negative to print that you would experience in the darkroom. It's all too easy to PS a negative scan in ways that, though it can be done, you don't have the skill to reproduce traditionally A contact sheet has the distinct value of being made on the paper you will use to make a print, which will allow you to make some assumptions about what to expect in printing that a negative scan simply won't. At least make both, but don't bypass the contact print.