It's not recommended to ride in a trainer with your road tire--trainers eat through tires, and if you have expensive tires, it's a terrible waste of money. Of course you *can* leave the skewer in, but it chews up the skewer and over enough in-and-outs it can compromise the lever of the QR. My trainer came with a spare skewer for precisely this reason. It's not difficult to swap them in and out, but if you frequently swap your bike from trainer to road it's a giant pain (more so with the tire than the skewer).

I didn't mean workout variation of that sort. I meant being able to simulate inclines, declines, and wind resistance. You can change your gear resistance and your pace in a trainer, but little else.