What exactly do you mean that it gets bad that your workout is affected because of your callouses? Do you mean your grip weakens? If so, the problem is your grip strength, not your callouses. I always found that they hurt more than they helped because they effectively made gripping bars HARDER. Sure, you get more friction between the bar and the hand, which might help somewhat, but with the addition of the glove you've effectively made the bar thicker, making it more difficult to grip. If your grip is slipping I recommend trying chalk first.
As far as a belt is concerned I've never thought of them as helpful because if your form is off on a heavy lift to the point that you need a belt, you probably shouldn't be lifting that much weight (with some exceptions).
The upshot of all of this accessory equipment is...what do you do on the day that you forget them?