VMC - reasonable viz.
Gatwick to Southampton - I have no idea of the actual heading but lets say it is 230 degrees.
Off you go using your HUD (because there be those that say with GPS your head is down in the cockpit) and point selected on the horizon heading 230 degrees.
Glance at the map (and with any luck the command bar also on the display showing your cross track error) and oooh bit left of track, select a new point on the horizon and give that a go. Within a few minutes you will have a point on your HUD that roughly keeps you on the "magenta" line.
No cross refering to your map, no worrying about whether you have found the correct ground feature you were expecting, just eyes up, an occasional glance at your moving map to check whether a small adjustment is needed and to confirm that the ground features look like those on the map.
Cant go wrong really.
Give it a try - you will be surprised how easy it is.