I've been doing 30-45 minutes lately and they are often piecemeal--2 or 3 short Jessica Smith "miles" or a 30-minute strength workout plus a 10-15 cardio. I don't usually go longer than 45 minutes because I almost always add on PT and/or core work PLUS stretching. The whole thing usually takes me over an hour, but I'm retired. I don't need to rush through workouts any more.
Donna