I wouldn’t back an outboard powered boat into a slip. I like the idea of having my prop and outboard away from potential obstructions (support cables, garbage in the water, shallower bottom, etc). Our tritoon and 99% of the outboard powered boats I see that are slipped in our local marina are pulled in forward and backed out.
A larger cruiser without outboards or something that’s got water level access in the rear only – yes back it in.