When will membrane and stitches fall out after extraction and bone graft?

I had extractions done on teeth #2 & #3 with bone graft and membrane. Followed up 2 weeks post op and one stitch was removed, but said the remaining stitches were still holding in the membrane and would be removed in an additional 4 weeks if they had not fallen out sooner. Is there any benefit to keeping the membrane and stitches in for over 3 weeks post op? There's no pain or infection, gums feel good, but the stitches are quite irritating and continually aggravate the cheek.