In my experience exclusion diets help to narrow down certain habits or foods to which might be causing those nasty symptoms to arise in the gut.
When my gut decided to flare up I tried for around a year to exclude different foods, calculate what I ate and keep a diary of the types of food I was eating. Here's a snapshot of what I did.
First removed Gluten and Dairy for 5-7 days to try and settle my gut down from being inflamed. Then only placed dairy back into the diet being careful not over do it. After doing this for 3 weeks I still had issues and decided again to reset the gut for 5 days then exclude dairy. However I still had problems and decided to eliminate high Fod-map vegetables and fruits, which tend to ferment in the gut. These included, apples, broccoli, cauliflower and bananas.
This had some success and I was feeling better so I carried this on for a period of time but noticed I would have flare ups as set times and that was post workout. So after doing some research I found that Whey protein was causing my issues and being a dairy product this made a lot of sense to me. Hence my need to switch to a vegan protein.
So in my experience this was my trigger and since then and with a steady back up of healthy gut bacteria I have had no issues and continue to enjoy a symptom free gut.
I have to throw a disclaimer in here and say that a visit to your doctor is always advised prior to completing an exclusion diet and I would recommend you ask for help on the types of foods and timelines your excluding foods from your diet.
This process worked for me and I'm a huge advocate, but it doesn't always tell the full story as stress is a huge factor behind leaky gut, and excluding foods only stops the symptoms.
Please throw me a comment for any advice or guidance.