I usually don't have a lot of time so my stretching is very brief:
I only stretch in the evenings, no time during the morning rush. I also don't have such a fancy routine.
warmup: 10 dynamic leg raises (front, side & back)day 1:
-PNF stretching: psoas, quads, hamstrings, buttocks
-relaxed stretching (30 secs) side split (adductors)day 2:
-PNF stretching (contracting 10 secs, contracting antagonist 10 secs, relax 10 secs): side split
-relaxed stretching: psoas, quads, hamstrings, buttocks
I keep alternating these.
Well I know it's very simplistic, but it seems to work, I measured exactly what you said for about a week, and there seems to be at least some improvement. I'll look for it and post it later.
Isometric stretches (contracting and relaxing the stretching muscle until maximum stretch and then holding for 30 secs.) I use 3 sets each of two stretches for hams, quads and adductors
Isometric stretches require at least 36 hours of rest for your muscles. But you do several quickly after eachother, most sources I've read state that that slows your progress down and that you should stick with only 1 isometric stretch a day, you can do relaxed stretches as much as you like though.
Edit: here are the values I measured this weak (in cm):
front (randomly chosen left leg in front, in the middle I noticed the other way is better but I persisted on that side) (not a lot of progress really): *(somehow I felt a pain in my knee so I stopped), 13, 13, *(ill), 14, 12, 11
side (some decent progress, too bad I was ill): 24, 20, 18, *(ill), 21, 19, 17.
Total gains for a front split 2 cm, side split 7 cm.