From a reviewer standpoint, as I understand it, a post qualifies as a First Post if it is the first question or answer ever posted by a user, and a Late Answer is similarly a first post, but also applied to a long-lived question. If this is true, from my experience reviewing questions and answers in the primary questions queue (outside of the review queue), I think the First Post and Late Answer qualifications are too tight and should be broadened.
In my time editing, I have encountered many Second and Subsequent Posts requiring review due to consistently poor grammar by Users who
- are fairly new, but have gained reputation arbitrarily
- are revisiting after several months, having asked one random question long ago, which disqualifies them as a First User even though they really do need to be reviewed
- are enthusiastic new users who post several consecutive questions
Posts from these types of users (and others) slip through the existing review cracks when in actuality, they should qualify for review in the same classification as First Posts and Late Answers, and it should not require attentive users babysitting the primary question lists to spot them.
I would suggest any or all of the following alterations:
- Based on my definition of Late Answer, merge it with First Post, since it's just a subset of First Post
- unless my definitions are incorrect; please correct any wrong-headedness in the comments.
- note you'll need to merge the review badge counts of all users
- Rename First Post to Inexperienced Post.
- Flag any post (question or answer) as an Inexperienced Post if the user hits any of the following ordered qualifications (note: italicized bold values were selected arbitrarily):
- had at least 1 post sitting in the review queue within the last 24 hours
- registered less than 1 month ago (optional: on all SE sites)
- has less than 50 reputation
- must not be single-sourced reputation (I registered my e-mail address; +50!)
- preferably determined using only post-based reputation
- optionally may be total post-based reputation across all SE sites
- has less than 5 posts total
- whatever other rules qualify a Late Answer / First Post
Implementing some of these may also solve the superficial problems of
- having hungry review queues
- reviewing experienced users of other SE sites, which is probably still necessary due to the variation of FAQ requirements between sites (I know I've needed review on other SE sites).