This topic has been on my mind lately, so I wanted to give some thoughts here as a new member.
I joined 2 months ago. 20+ year musician, mostly rock but well schooled, and brand new to music licensing. Focusing on instrumental cues, which I am also brand new to.
My main interest in Taxi was the review system, as a sort of fast track education into this business. With no expectation of getting anything forwarded for quite some time, I planned to use the reviews to learn the ropes and see where I should improve. I find Taxi TV extremely useful and fun, but I am VERY busy in life and probably only catch 2-3 hours a month.
I've submitted 7 tracks to Taxi, which I spent a lot of time writing specifically for the listing. Going to speak loosely here as I don't believe there's datestamps on the reviews (though maybe I could line up the email notifications?).
I've had a couple come back in less than a week, and the rest are taking 4-5 weeks. Longer than I thought!
That said, I've been very pleased with the brief but kind and actionable feedback I get. And I've managed to avoid the dreaded "too midi" so far!

As a newbie though, the length of the review time has been frustrating. Obviously it's so difficult to put things into action when there's such a lag time, and kind of drains the motivation to slave over a song for a Taxi listing in my limited time if I still have so much pending feedback out there and may just make the same mistakes.
I'd been figuring reviews would 2 weeks or so, based on honestly nothing in particular.
I guessed things were slower due to covid (and hopefully an uptick in business from homebound musicians?), and also after searching around the forums learned things take longer than I thought in general. So although frustrating for a new person, no hard feelings really.
Was in the dumps about it briefly, but came up with a strategy and am a happy guy again. Unless something just perfect for me comes along on Taxi, I'm going to sit back and wait for a "batch" of reviews to come back. Meanwhile, I am practicing writing and mixing a LOT, and sending the tracks off to the stock music marketplaces (Songtradr, Pond 5). Of course with the risk that some of those may be a good match for an exclusive Taxi listing I'll have to pass on.
But it's been worth it, as I've got so much practice writing MORE music FASTER. And I feel like I will do so much better on my next "batch" of Taxi submissions.
TLDR: Taxi review time is rough on a newbie, too hard to integrate the feedback. Still happy with Taxi, in hopes it'll get me into some pro libraries eventually. Until I get much better in tune with Taxi, I am going to oscillate between a flurry of finely-crafted Taxi submissions, and a flurry of more quickly-written open market submissions to hone my chops.
Sorry for the long one.