I've installed an oversize box (8x8", 10x10", etc.) off to the side of a new panel to collect these short runs. I connect that box to the panel with a short length of 1-1/4" or 2" conduit. Upsizing the wire isn't an issue, as the runs are too short, and need to be spliced anyhow.
IMO it looks much more professional - and intentional - than a bunch of scattered 4x4s.
