I am at 35 goals now. I am also beeminding Habitica, which has much more.
Some of my goals are microhabits: 200 hula hoops a day. Some push-ups. Some belly crunches. An aromatic stick. Moisturizer. Etc.
At some point, I feel Beeminder UI stops scaling. And I mean, visually scaling. So I am not adding more goals where I really want to.