Heehee, well like my youngest that used to work decorating cakes always says, none of use would ever be hired by a bakery, haha!
Gosh, I vary a lot, sometimes, like for a Barbie cake, I can do it in about 20-25 minutes for the decorating part and the baking and making the icing is about 1 1/2 hours. Character cakes usually less than or around 1 - 1/2 hours. But wedding cakes, well I spend way more time on those. Plus if you make gumpaste or fondant flowers, they can take many days to do.
Buttercream transfers, well I can be slow at those. All of that mixing the colours and lttle areas to fill in and such. Plus I make separate icing for it and usually do it ahead and freeze it at least overnight or a couple of days or weeks.
I find some things easier to do, others harder. Plus if you are doing a lot, you need to take breaks because your arms do get tired.
Don't feel bad, it can take a long time to do a cake. So we might not be able to work in a bakery and we may be working for peanuts, as long as we are happy with the results, right?
It is the darn cleanup afterwards that takes forever and it is just what you feel like doing, right, haha!
Hugs Squirrelly Cakes