Ewker, I will concede that each personal set-up will have its "optimal" hang distance. Hammock and tarp size are factors so I should have clarified what I mean for my set-up.
I often use the GoLite Poncho as my shelter. The GoLite Poncho Tarp has a ridgeline of almost 10 ft (3 m). This past week I also used the Hennessy Cat Cape tarp that has an 11 ft (3.4 m) ridge line. I only need anchors that clear the tarp plus a foot or two on each side for rigging.
As you noted, many tarps have a ridge line of 11 ft (3.4 m), so a distance of 12-13 ft (3.5-4 m) works just fine, as long as you have your rigging optimized for this distance. For example, traditional Whoopie slings with a minimum collapsed distance of 18 in (46 cm), don't often work. This is one reason I use a continuous loop at each end of my hammock and can connect directly to my strap instead of using a Whoopie + strap. This reduces my pack weight a little, shaving grams off of my straps and suspension, although I often bring a pair of short Whoopies (3-4 ft/1-1.2 m) for "just-in-case" scenarios.
The DutchWare Stingerz also help with these close-in pitches because I can rig it up right at the end of the tarp with ease.