They take me about 15-20 minutes each, on average. I usually have on the order of 12 photos to upload...again, on average. I have had a few that take a little longer because I have to take a few more pictures, but I can take a picture in 1-2 seconds. Even if I had to take 100 pictures, it only takes 1-2 seconds each to take those photos-which would be about 3 minutes of actual picture taking, so I'm not sure how I could productively spend 4 hours at one location.
I have done several hundred of these, I make routes of them, and they are spectacularly easy once you get the hang of them.
On the other hand, this particular brand takes the longest to enter on the archaic site. The green station take about half as much time to enter as Shell does.
Do not be put off by the long form, they format it to look like it has much more to look for than you really do. It's because of all the drop down boxes with choices for 'no' answers.
The manual is thick, but that is because it has lots and lots of pictures that are large enough you can actually make out what is in them.
My first one probably took me a half hour...just to get used to what I was looking for. I can do them on automatic now, and very rarely have anything come back for clarification.