Yep, just about every week. When you first start doing forms "in public" you will feel self-conscious. This is part of the training, IMO, and overcoming it is a definite step forward (letting go of the ego part of you that cares what other people might be thinking while they're watching you).
Our instructors have scheduled full classes at parks or at the beach, partly for that reason and partly just to get out and enjoy nature.
I have worked on forms on the street in front of our house (no backyard), at parks, at the beach, in foreign countries, etc. Occasionally I've had someone heckle while driving past, and once I had a couple of people come up nearby and conspicuously start wrestling with each other... I ignored them and started in on a weapons' kata (3' staff) and they shortly lost interest and went away fairly quickly.
In choosing a spot (on those occasions where I can choose), I think it's important to pick somewhere a little out of the way... in other words, don't go into the middle of a busy public park with families all around and a "look at me" attitude... if you go a little ways off to the side, you'll find that most people will ignore you, some will watch for a little while before getting bored, and a few may approach with questions. Strangely, the better you get at your forms and the further you have progressed in your training, the less likely you are to be bothered.
Now if I go somewhere new to train (by myself, as I recently did in a park in Italy while on business), I usually feel self-conscious for about the first run through of the first kata. After that, the feeling disappears and the forms just flow. I always feel fantastic after doing this type of workout for an hour or so, and it always makes me wonder why I was reluctant to do it in the first place (see the ego comment above).