Us gals have a little problem when trying to play the fiddle not under the chin. For some gals it's a much bigger problem.

I got a good chin rest last year, a fairly high one, so I can play without the shoulder rest for a little bit if I choose. But it is SO much better, for me, anyway, to play with the shoulder rest, especially for a long practice session. If I can only get in a few minutes, I'll do without - but I have noticed that it's true, you expend more energy holding the fiddle that way.