I love in Colorado, which is a pretty dry state, so while I had heard of "wet filament", I never considered it to be a problem that I would have to worry about. I had seen people creating dry storage bins for their filament, but figured that must just be for people in humid climates.
When I first bought my 3D printer a few years ago, I did what most people probably do - I bought a 10 pack of different filament colors. Everything printed great for a while, but eventually, my prints just started to kind of suck. I made a few upgrades to my printer, but still couldn't pinpoint what was going on. What was frustrating, is that some times my prints would be great - but other times I couldn't even print the most simple prints without problems.
I eventually noticed that my great prints were from newer filament that I had recently purchased, but my bad prints were coming from spools I've had sitting out for a while. So I purchased a $40 filament dryer on Amazon and it instantly fixed all the problems I'd been having.
I feel dumb, because I had gone through three different extruders, new hot ends, new nozzles, tubing, and spent tons of time cleaning and tightening stuff on my printer. I had left my printer untouched for months because it was just so frustrating. Something as simple as old filament left out never occurred to me until much later.
TLDR; If your prints have started to suck after a while, you might want to try drying your filament.
Most dryers now allow you to print directly from the dryer. I keep my spools like most in cereal boxes with a 100g dessicant sack. For pla I just throw it in dryer, set a timer on it, while I'm prepping my bed and print. Works well. For PETG or tpu I like to try to let it dry in the box for a couple hours before getting started. If you are not carefully keeping filament dry and switch to a sealed dessicant system, I would recommend putting the filament in a drying box for 8h prior to then putting it in your storage container. I tried vacuum bags for awhile and the cereal box thing is way less of a pain.