I'd estimate a third of my commercial accounts are in and out. A lot of guys prefer to do just outsides. Less money, but usually far higher profit. Some, like me, will do insides. It can be a pain, but it increases the 'wow factor' and makes for a full-service company in that respect.
I'm with Tony on the tools. Separate is fine and really more versatile, especially if you use quick-release squeegee handles to change channel sizes when needed. Also a swivel handle will help with weird angles you may encounter.