Making a film for partner how long is too long?

Not long ago i made a masturbation compilation all in slow motion, So
obviously it was longer than it would be normally coming in at 30
minutes, I thought it would be too long but she enjoyed it alot. This
time i want to make a edging video for her (not in slow motion) this is
something new for me and something my OH has never seen, As im going for
a edging video its going to be longer than normal masturbation but how
long before it will get boring?