I came from the traditional charity fundraising world and repeated asks are the norm. As you say, if you don’t ask, you don’t get a gift. I don’t agree about running specific themes once a year, it puts teams at a significant disadvantage if their timelines don’t match the schedule. Having the grants round is also a stewardship opportunity to feed back to the community that supported you.
One way the regular charity world gets around the repeated ask problem is to sign people up for monthly recurring donations. I think many donors would be happy to say “I’ll give $2 every grants round automatically”. We would just need to add that funcitonality.
I like the idea of categories to highlight project themes or two enable better searching (it’s much easier to say, I want to support projects based in Africa and have a category for it rather than scanning all of the projects), while leaving the round open to anyone to participate.
Donors also tend to give small amounts each round because of the matching. I think if they only had to opportunity to give once a year, you wouldn’t see those $1 donations turn into $10 donations.