I don't ask, because the answer is always no.
I just say, "I have to go to the bathroom, let's go together." Sometimes it takes a few tries to get her into the bathroom. I might have to remind her that we can read a story together on the potty. Once she's in there with me, she always eventually decides to go. Sometimes she wants to wait a few minutes, which is fine. I just don't want to try and force her to sit on the potty.
Most of the time DD goes about every two hours, but she also usually has to go immediately after a meal, no matter how recently she's gone to the potty.