Massaging the penis head with vaginal muscle contraction

We are married for 20+ years and have exciting sex life. We always manage to orgasm almost at the same time. Our sex session will usually take 45 to 60 minutes and most of the time we are in missionary with the penis inside the vagina. It is exciting to count the penis strokes so that you keep on going without climaxing unexpectedly. We found that at every stroke if you withdraw the penis completely and then re-insert into the vagina while the vaginal muscles are contracted my the female. enhances the sexual pleasure for both. Try to keep the head of penis at the level of the vaginal entrance when the female contracts her muscles of the vaginal entrance voluntarily. We can go on for minutes with this newly found pleasure of massaging the penis head with wife's vaginal muscles which she can contract at will.

Has any one got similar experience to share?