I have a fairly good idea that the less change of locale in a play, the better. So, for instance, if the first scene were to take place in a living-room, the second a restaurant, and the third a garage, would that pose logistical problems? Most of the play will take place in the living-room. The play is only for a few actors, so I'm not dealing with crowd scenes.
Don't let the logistics of production inhibit you in your writing...leave it up to the design team.
I've seen plays with multiple locations easily staged using "periactoids" (I'm not sure of the spelling)...three sided set pieces that are spun around to reveal the next location. But don't even worry about it...write what you need to write.
Out of all of my full-length plays, only a few are one-set shows. A show that was produced last fall had 5 different locales, and it was all done very easily and simply in a black box theatre. So I agree, don't worry about it. Write what you're going to write, and the set designers of your productions can figure out how to make it work.
On the subject...as a producer of site-specific theatre, I find people are too limited by the wheres of a play. Here I am, desperately hunting for plays on fire escapes, in fountains, under the sidewalk grate....and I get - park bench - park bench - park bench, park bench, park bench.
Basso, a play of mine about Hurricane Katrina was recently produced in a black box with no scene changes at all. I had written "Scenes may be suggested" when I submitted the play and that's what they did. First the town hall, then the town after the hurricane struck,two characters waiting at a gas station, two characters affected by global disasters (no setting even suggested by me) three characters on the road to the Houston Astrodome and finally in the Astrodome, all suggested except the global disaster scenes, and furthermore it worked, according to the review.
I like to set plays in as many different settings as possible but last year I also wrote a two-act play set in a kitchen, with only one scene in each act. I had to have lots of exits and entrances but I figured if Beth Henley did it in Crimes of the Heart, I could too. Now if only I could do it as well.