for mse walls, some charge by the s.f., never have to make an engineering decision since they try to get the geotech to specifically tell them all the parameters to input in to their $400 program, and then disclaim all their responsibility on to the owner. somehow, these "leaches" try to justify expecting the site to meet their design instead of making a design to meet the site...but i suppose that would require real engineering. in other words, it's a fee for zero liability with little to no actual engineering involved...you just use the "cook book" method of selling the same design to client after client.
cap07,in all reality, it depends on the job and client. i've seen all the methods you mention (and even a combination).