I don't know if they still do this, but Skyschool used to to credit us with any non-flyable days and we could either extend a week or go back another time. I did 2 separate weeks and paid for 1.5 weeks. I was never rushed to a qualification, it was always dependent on completing the training log. My last day I only needed one more flight to complete, but the weather was murky, low cloud. My last flight needed a spot landing, engine off from 1000 feet. This was discussed and I had the option to either do this and get my wing damp, stay another day or come back a different time. I did it was done with zero wind (and I mean zero), but the low cloud got my wing damp. Visibility was ok, just a bit damp. With the incentive to get it right, I landed on the dot!