I’m a little late to this conversation, but I have a few thoughts.
First, quite some time ago, I put a lot of thought into how I should store (and recall) the random notes that Drafts lets me create. One immediate realization was…if you can’t find it (or simply never see it after you write it), you’re really just hoarding. What’s the point of keeping a note for future reference if you never refer to it?
So, I set up my Drafts Inbox to only hold untagged drafts. In my worldview, untagged means unreviewed. The badge on my Drafts app icon tells me how many unfiled items I have at any moment. And that little red badge motivates me in my continuing quest for “Inbox Zero”.
I’ve also finally accepted that, no matter how much I believe I will do it, I really never get around to reviewing later, even if I schedule a regular time to do it. I still have a “GTD review” reminder that pops up on my phone once a week, and I can’t remember the last time I actually did that.
So I try really hard to tag drafts as soon as I create them. This requires me to keep my list of tags thin and realistic. I try not to create a new tag unless I really think I will use it regularly. I need to be able to remember my tags so that I can recall the right one whenever I create a draft. But I’m also not hesitant to create a new tag when the need arises. Tagging an item with multiple tags helps me perform effective searches.
I use workspaces (which are really just tag lists on steroids) for projects and specific types of work, like “writing” or my “world domination” business plan. But in many cases, my drafts are just tagged and not linked to any particular workspace. If I’m working on a particular project, I’ll open that workspace, but if I just want to find a piece of stored data, I’ll just filter by tag. In many cases though, I’ve found that Drafts’ universal search function can find what I’m looking for instantly, without even needing to sort through tags or workspaces. That assumes that I can remember a specific enough keyword to search for.
I do review my Inbox (containing all untagged items) periodically (whenever that little red badge starts bugging me). But, to be honest, I actually spend more time cleaning out my tags list. Sometimes I’ll rename a tag, or consolidate two tags into one. The tags, and the workspaces that depend on them, keep me organized.
Occasionally, I’ll pull up a tag and review all items with that tag. I don’t do that often, but it’s good to do a little housekeeping every now and then.
I don’t use Drafts for lists. I use my iPhone’s Reminders app for that. But I do send items to that app via Drafts.
I’m also picky about which items I archive after sending them somewhere else (like to a text message or an email). I find that, in most cases, they can always be found there and don’t need to clutter up my Drafts repository. Most of the time, if I send it outside Drafts, it can be trashed.
One last suggestion: After you set up your Inbox to show only untagged items, pick a word or exact phrase that you think many of your related drafts might contain. Do a universal search for that word or phrase, and tag all the resulting drafts with a tag. I think you’ll find you can process a huge number of unfiled drafts that way, leaving a much smaller number to be reviewed individually.
Always interesting to see how people use drafts (extensively) to get inspirations of what’s possible 
. As for when, well try some experiments. Does first thing in the morning work, to catch you up on what you were thinking the day before? Do you stop for coffee at 10 in the morning and that will work? I used to have a regular timeslot just after my son came home from school while he was having a snack. Basically, it’s far more about workflow, rather than tools in my experience.