Which reminds me of a vicious circle that can happen with ukemi. Nage throws me in a way that doesn't require a breakfall, so I don't breakfall. This causes nage to conclude (incorrectly) that I *can't* breakfall. Which causes nage to throw me as if he's afraid I'll break. And so my ukemi looks tentative because I'm not sure where nage is trying to send me. Which makes nage's throws even more tentative... Sigh...
ya know uke can choose what kind of fall they take a large part of the time. Iv'e shocked the snot out of my training partners on more than one occasion by taking a breakfall out of his throw rather than the expected roll. My particular favorite is to take them off of the end of the jo, in jo tori kokyunage.
We don't really do a lot of breakfall practice in my dojo but I enjoy taking a few now and then so I just go ahead and take them. Of course when I want that I go find a training partner that I know will thrown me with a lot of energy.