I also used to cut out caffeine the week before an A race but I got headaches and felt terrible so now I cut down to just 1 cup a day until 3 days out then cut it out completely.
I read somewhere that caffeine’s effect runs out after a few hours so on 70.3s I didn’t take any until the run and in IMs I had a Redbull after 60 miles… this does work and gives you a real boost when you need it.
Reading other people’s comments I’m now considering caffing up from the start and simply taking more!
I also read somewhere that 5mg /kg was the recommended amount… for me that equates to 6 cups!!
Edit: it’s actually 3-6 mg/kg
https://www.britishcycling.org.uk/knowledge/article/izn20140516-Nutrition-Cycling-Supplements-0