I gained about 15degrees of motion in my open straddle split in about a years time, and am still about 10 degrees from really being able to be 180degrees out and roll forward.
I gained similarly about20 degrees of motion in my front back splits (both sides) and am currently about 6 inches from the floor.
I stretch twice a day, hold each position for 20-30 seconds. I figure I am a year or so out.
I almost tore a tendon loose from a bone in my knee being "slighly too agressive" and have since taken a more conservative approach.
This expreience is from a person who was capable of doing all 3 splits about 15 years ago.
So, I reinforce; dont push it to far.[/i]