So every video took me roughly 4x to do (because I'm learning). So 20 minutes = 60-80 minutes :D.
How long would it take a pro to do this entire chest?
In my experience, a pro should be able to complete this entire model + texture + materials in 4-8 hrs assuming they know what they're creating (i.e. not researching / conceptualizing what kind of chest they're going to build). 4 hours if they're in the ZONE and 8 hours at a "normal" pace.
I say this only because a pro would have a lot of experience working on these kinds of assets: Nothing new to learn, just execution. I guarantee if you build the same chest again from scratch you'd surprise yourself at how much faster (and probably better) you would work.