What is an acceptable page-for-money ratio?

Currently, I am working on a grant for European money to work in the homecountry. This grant asks for a ridiculous number of pages where you have to tell them all about the proposal (in a variety of different ways) (7 pages), your own competence (5 pages), something called implementation (4 pages) and impact (5 pages). All this work is required for 4 years of about half a senior post-doc salary. Half! So not even an entire salary, or extra money for consumables, travel or another person. Still, I’m doing it because any extra money is good and there is only a limited option in terms of which grants to apply for. However, I do think it’s a pretty ridiculous amount of money when you look at what you get, especially compared to another foundation grant I applied for that is a similar amount of money but only asked for a 2-page proposal and your biosketch.

So my question for this afternoon: what ratio of pages/money is acceptable and when would you decide not even to bother? (I understand that the percentage that is funded is also a factor in deciding whether to apply but that’s for another time).