Isla only has the one a day & not even every day. If I don't feel up to having her on I say no.

She was sick over the last few days & while I was worried about passing on the bug she had to Iain I still let her feed & then washed my boob before going to Iain (she had a gastro bug, vomiting etc).
When she has had a BF but asks for more (she has one before bed if she is going to get it) I say no but get her to hold my hand. Which she is quite happy to do.

If you think he is doing it mostly for comfort then maybe try offering something else. Also distraction. I know its tiring but when your ready maybe when he askes time & time again during the day ( yes I do think that 8 feeds a day plus an overnight feed is excessive but not saying you shouldn't just that I wouldn't) maybe you could say not right now, lets go hang the washing, check the washing or check the mail. Just somehting to distract him for the moment & get him to help you with something. I would say he is feeling the need to make sure he is still your bubba. Try to encourag ehim to be Mummy's big boy & get him to feel special helping you with special big boy jobs.