I personally don't think it matters how you split up your weight routines, as long as each muscle group is getting its share of work over the course of a week. I think your split is a good one ... it really makes no difference what amount of time you put into a given workout, just that you are covering all the bases. As you progress, you can change things around so you will continue to benefit from the lifting.
The variables to consider are summed up in the word FIT ... frequency, intensity (poundages) and time. As you progress you can ratchet these up a bit or if you want to just maintain, you can shuffle them around to make up new, fresh rotations.
A beginner might want to do a total body workout three days a week. She might use two sets of two exercises for each body part. This could take approximately 30 minutes, but she'd get the same benefit from dividing the body in half and doing 15 minutes in the morning and 15 in the evening (although she might lose a little of the already limited cardio benefit from the workout).
If she's getting more fit but doesn't have more time in a day, she might start doing splits similar to the one you're doing, but covering more days in the week (frequency) ... since she's only doing part of the body now, she might want to up the poundages (intensity) and after awhile, add another exercise that extends the time each workout takes.
It's an individual thing, IMO. No one system is the be-all and end-all in weight training.
Looks to me like you are doin' fine!