Where to install bypass closet door floor guides 23-029B

I am thinking of replacing our bipass closet door tracks with the subject items. My doors are 3/4" thick so might work. But where the guides would be placed and how many are needed for each pair of doors is unkown by me. Please tell me if you can whether 3 for each closet would do the job.

I'm picturing one in the middle which would be actively guiding both doors at all times and one toward each end of the door runs. But wouldn't the end ones be sticking up where one might step with a door open, if not placed at the edge of the run where they couldn't effect the guide activity very well.

Hmmmm....would love to talk to someone who knows this. Thanks, -Ron in Oregon