[gastroturf]

For myself, I try to keep it less than 3 simultaneously.

Optimizing for quick disqualification allows you to reduce total time cost. Filter based on roles most likely to advance your long term career goals.

Be mindful that a prospective company that imposes significant time cost on candidates in the interview process may also not be the most humane cultures to work with. You can filter them, just as they filter you, but this may cost you opportunities- only you can evaluate that choice.