When MSFS first released, up until the XBox release, they only had 1 person doing QA and putting products in the store. The maximum amount of products that could be added or updated was only around 10 a week. Once XBox released, now there were a lot of products that could be released to XBox (but had to be done separately since they have to be tested for XBox). To make matters worse, that was the infamous SU5 which then sparked off a whole constant iteration of developers having to release patched products. All of that held up the glow through, and things got backed up to almost a 4 month wait time for releases. So they hired 4 more QA people. So now they can get about 50 additions/updates a week done. But keep in mind, if a product releases for both XBox and PC, then that is two spots.
Now I know people say they don’t really do any testing, but they do. They fire up the addon. They check to make sure it meets product guidelines (like does the plane have any weapons on it), they make sure it has no viruses, they make sure there isn’t code that is constantly reaching out across the internet in an unexplained way. Where there have been mistakes in the past, XBox testing is actually done on a PC using an XBox emulator, but that was allowing WASM to run, whereas on a real XBox WASM could not run at all.
So at one point, backlog had gotten back down to about a week again. But there are lots of products lately being released. If the volume each week goes up and stays there, I’m sure they will hire more people to get the backlog back down.