Does sleep training ever stop?? We've been through it twice but it seems every 2-3 months he slides back to needing us to pat him down to sleep.

I’ve found this article which suggest that there could be some sleep association that is affecting your sleep training. The writer recommended simply changing the bedtime routine to help rectify the problem. For example, if you have a night feed just before you put the baby to bed, the baby would have associated eating with sleeping. Change the night feed timing to 20 mins before bedtime may help. Make changes to the activity that happened just before bedtime for five days consecutively and see if it helps with the issue. It was effective for the writer, hope it works for you too! https://www.preciouslittlesleep.com/when-baby-sleep-training-doesnt-work/

My friend's toddler underwent sleep training successfully for 4 months and recently he went back to needing his parents to be there to lull him back to sleep. Apparently this was due to a change in his daytime patterns -- he used to take a nap in the late afternoon but because his mother went back to work, there was a slight disruption to his nap times and this totally messed up his night time sleep training. Perhaps there was a change in your toddler's daily routine?