As others have said, it will depend on the truck and 5er.
My first set up, a '99 Ram short bed and 1998 Dutchman 5er never needed a slider.
My next rig, an '03 Ram short bed and current 5er, needed it just about every time I backed into a site.
I had a Reese 16k Qwick Slide, and that thing was PITA to use, I had to drop the landing gear and remove most of the pin weight to get it to slide. I finally upgraded to a Superglide, which was great for manuevering, but it must weigh over 200 pounds, and was a PITA to get out of the truck.
Most things in life are trade offs. This is one as well.
2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010