Experience with “don’t offer, don’t refuse”?

I have a lovely 15 month old boy. He is exclusively breastfed since day 1. Drank pumped milk from a bottle 2 times in his life. For the last couple of months he is ALL DAY on the breast! There is no moment he will see me sitting down and won’t come to pull my shirt and he wants it to be open and available all the time, otherwise he will scream and get mad! I am trying to start with the “don’t offer, don’t refuse” method but we end up nursing the whole day, as I don’t refuse unless it’s really getting annoyed. Any similar experience or advice?