Good morning mate , this is a good ideal and judging from the looks of it will really be effective in the Nigerian board but once a year would be too long well it will also be nice to hear other users perspective on this topic
On a second thought as you noted yearly is a long time. Making it monthly may not be bad so that it can be easy for the team who will be in charge if the proposal is accepted to access members contributions for the month. I think making it monthly will be more feasible and competitive. Members may not have that flair if it's done yearly.