we probably go too much but we are trying every 15-30 minutes.  He seems to go every single time so I think that is working for us.  I think you may have to experiment with it.  My sister swears by the "nakedness" method of letting them run around with no clothes on but  I just can't do it.  I kept walking into puddles. 

I think you have to try a couple of different things.  Every comment you got here seems worth trying.  Good luck to you. 

i found more success without the pull ups. My daughter thought they were diapers. I took them away and she had some accidents on the floor. I used pull ups at night time. I found that she got upset when she peed in her new underwear. i put my daughter on the potty when she first got up, midmorning, lunchtime, before nap, after nap, dinnertime, and bedtime. Best of luck!!!

What's been working well for us is this: about 5-15 minutes after eating/drinking, before and after bed/nap time and activity, 1 hr 15 mins after last potty trip/accident.  It's mostly training for them to get used to sitting on the potty and if you're using rewards, I think they look forward to it.  My daycare provider says she puts her children on every half hour.  I think it may be too excessive, and I get too worried that it might turn them off from the potty completely.  I think you'll learn your child's rhythm after a while and can adjust to that.  I also try to remember to go to the bathroom before we sit down at a restaurant (either to potty or wash hands).  Good luck!

My niece had a talking potty and she would not potty train after that. She was afraid of it. Incase that happens(to where he dont want to go potty) you will know that it could be the "talking potty" But after my mom got rid of it, she would go potty again. Just a little tip!