Do quick workouts throughout the day help?

I'm trying to build muscle at home just by eating a lot of protein and healthy weight-gain foods, and working out with pilates, pushups, and on my hangboard (used by climbers, you can do all kinds of pull-up type workouts).  So far I've found that it's been working quite well, but my problem is that during the week, I don't have time to devote a solid hour or so to work out.

I work from home, but I don't take long breaks.  However I have been stopping to do 10 or 15 pushups at a time whenever I walk by my perfect pushups (GREAT tool!!  work your muscles way more).  Is this going to help me build muscle at all?  Or does it need to be a heavy workout?