That will depend on what your shooting. If shooting conicals you might get a few shots off before needing to swab. When you load, your sense of feel will tell you more if you need to swab then anything else. With sabots I would recommend you swab between shots for the consistency and accuracy the swabbing will add to your range session.

What to swab with is a good question. Talking to some Scout owners they advise that the Scout can be temperamental in terms of igniton, and especially on wet days. For this reason I would only swab with isopropyl alcohol. Alcohol will draw fowling out of the barrel, it will dry on its own or with a few dry follow up patches and alcohol will burn of course.

Swabbing correctly is the key. Dampen, not soak the patch. Work the barrel in short strokes, getting longer as you work down the barrel. Follow with a dry patch. And never push a dry patch down a fowled barrel.