That doesn't bother me, to be honest.
What is your limit?
I guess it depends on the time I have. I appreciate it when I'm told "this survey will take about 15 minutes to complete", or "this survey contains 15 questions". Then I feel I know where I stand, and I can wait until I've got some time available. (It's an excuse to get a cup of tea!)
What really annoys me is when new pages keep appearing and I have no idea how many more there will be, or how long the survey will take. Sometimes I just abort in these circumstances.