I have written a few that I use frequently. In at least two different sections of the BCP are prayers re specific subjects, and I have xeroxed several of those as well. Years ago, I created a prayer list of friends and relatives, divided it between the living and the dead, added the prayers I had chosen, xeroxed it and then used a copy machine to miniature it to one page that fits on the front fly leaf of my prayer book. It is a big help, especially now that I'm old and my memory is shot.
I'd be interested in reading your personally written prayers if you want to share.
God made the country, and man made the town. William Cowper