My roosts are 4' off the floor. My chicks ( 19 wks old) sometimes use the ladder and walk all the way up, sometimes only walk up a few steps and then jump the rest of the way, other times they fly up from the floor. Same thing on the return to the floor. sometimes using the ladder and sometimes just jumping down.
So i think put in a ladder that way they have a choice. I used a ladder when they were in the tractor and the roost was only 18" from the floor, they still did the same thing as now. give them an option.