Like most Area51 users, at any given time I am following over a dozen proposals. Frequently (especially regarding newer proposals) I only find a couple of Proposal Questions that I feel are worth up-voting, and as such I must return later in order to make my full contribution to the proposal.
Followed Proposals list in profile
I would certainly understand the sentiment that users should often return to followed Proposal Pages in order to keep tabs on their development without further incentive, but I feel it would be exceptionally useful to have an "Available/Remaining Upvotes" count and a "Available/Remaining Questions" displayed adjacent to my followed proposals in my Area51 profile.
"You can create x more questions for this proposal." message does exist on Proposal Pages, it is fairly well tucked away. And, to the best of my knowledge, in order to assess how many upvotes you have remaining for a particular proposal you have to visit the Proposal Page and attempt to upvote something in order to receive your count in a notification box. Alternately you can click on the "My Votes" tab (which is really just an order-by filter that still lists every question that you did not vote on in addition to those that you have) and manually count the upvotes. It would be great if these numbers were given more predominate real-estate near the top of the Proposal Page.
In this manner, users could quickly assess which proposals have yet to receive the benefit of their full contribution. Additionally, it would deter users from attempting to upvote more than 5 excellent questions or attempting to add more than 5 questions, which can become considerably annoying depending on circumstance (in my case, manually re-visiting every Followed Proposal to try to figure out which ones I haven't fully contributed to yet).