I do them every 2 weeks to a couple of months and constantly change it up. I currently use Sunflower Oil, OJ and egg yolks. I've gone 4 consecutive flushes with nothing - not a speck, not a flake ... nothing. Then, I was back to production again. I had a significant output 3 flushes ago. The last 2 were pretty light. I do them, just to do them. My initial motivation was shoulder pain from a pinched nerve. It alleviated that pretty quick. Also to reduce my cholesterol. It never affected that in isolation, but combined with other other protocols, it's gotten down.
ESF? Epsom Salt Flush? Haven't heard that. Unless you're just talking about using it as a standard laxative. With Salt water Flush - I do them a lot. On empty bowels (as a rinse, not as a laxative - you don't want obstruction) I start with 2 glasses of water, an hour later a quart of SW, an hour later another quart of SW. Sometimes, I'll do a third quart directly or drink more fresh water first. The first effect hits you in 1-2 hours.
Usually, by the time it's run it's course, it's virtually clear elimination