Screenwriters who are in the process of marketing and selling their screenplay often ask how many screenplays they should have in their repertoire. While screenwriters, might want to have more than one screenplay, it is important that it is your best work, for you to feel like there is know where else you can take it. I also think it is probably a good sign if everyone around you — your fellow writers, your family, your friends, and local writing groups, have read it and provided useful feedback to which you have considered and rewritten accordingly.
If people are having problems with your screenplay, then you probably need to take another look. There is not an actual number. I think it is probably more than one. The more important thing is that you feel like it is your best work, and that you have become honest with yourself about its quality. I think that is often the problem with which screenwriters are not comfortable, or they just want the struggle to be over.
As a screenwriter, writing is the hardest part of this whole process. It is not submitting or querying people, and they want the hard part to be over. If they can somehow convince them self that they have product that is ready that’s a good feeling but the best thing for us to know is to be humble, honest, and to know that maybe we aren’t ready, and to go back to work on our script.