Can you change default "add caption" length?

Hi! I'm putting in some open captions and I'd like to change the default "add caption" length. Right now every time I hit add caption It gives me a new 29 frame space to put in new captions, so I have to manually change the length to 3 seconds each time. This is tedious, even for a 3:30 video. Please tell me there's a way to change that default length.