I've worked in a number of offices, and visited maybe 30 others.
Taking DPS out or not is dependent upon the individual situation. Where I am now we have multiple coverages, lots of DPS, parcels, LLV, upscale suburbia with easy no blockage curbside mostly. I realize most rural routes have much less DPS and far more boxes than we do. If I had 500 DPS and 1000 stops, I'd take it out. But with 2500 DPS and 400 boxes, with coverages WSS or Boxholders that make tremendous dividers, it's far faster for us to case and deliver -- as the only time advantage we get is maybe longer EOS time if we throw everything from taking it out into a pile and slow sort when we get back. ( actually I believe if we case DPS we are allowed to take the pile of crap out of the office and sort when we return, so no real lost time there) In our case, "fast" doesn't harm us under RRECS. We do have several in each office who take it out, but if truth be known, they do so in order to stop longer at each mailbox and customers are used to meeting the carrier for a bit of social talk, what the carriers call "customer service"
Having worked city as a dual for five years, I'm very comfortable taking it out, that's not the issue as it might be for some. However, by casing inside, there's far less sorting and work in the vehicle while on the street, and this seems to make operating safer because our eyes are on the road and mirrors, not looking at mail and flats.
We can STILL deliver deliberately, taking time to be sure to perform every function for credit. (My current route is residential, but about ten home businesses on it, and every one is a "customer pickup" and "prepaid acceptance" scan)
Now, since maybe 90% take it to the street, (little difference than city carriers) go ahead and blast away at me!!