Unlike LE/MIL students who have to be a cooperative trainee, real people will not just stand there and let you do it to them
They duck, bob, weave, turn away, put their hands up to their face to block it, move, etc. etc. etc.
Move to a superior position, spray from different angles and at different targets in the facial region.
Use P for plenty and you'll get through.
All the above to be IAW policy, law, etc. and reasonable to achieve a legitimate LE objective.