I've been pouring a ton of time into researching spousal sponsorship since early 2020, and everything I've read of other people's experiences shows me that they absolutely do not process in order, and also that the call centre doesn't know what they are talking about most of the time.
Take everything they say with a grain of salt.
If they really processed in order, there wouldn't be people who having been waiting over a year since their last update. I know that there can be issues with applications that make them take longer, but that doesn't explain people who do everything perfectly yet have to wait far longer than most.
I think they really need to overhaul how everything immigration related is done internally, because clearly it isn't good enough and we are the people who have to deal with it. It's way too confusing, inconsistent, inefficient and takes forever. The fact that they will take 8 months only to return an application and restart the entire process of waiting, just because you got a single tiny thing wrong is completely absurd.