I assume by "lugging" you mean large throttle openings at low rpm, such that the hydrodynamic lubrication between working surfaces breaks down, causing rapid wear.
For me, not large but minimal throttle openings. What I know as 'lugging' is the feeling of an engine beneath me which feels lazy and that any 'awakening' from its slumber would cause undue effort on its part without changing into a lower gear.
Here in Australia we have a vast number of speed limits on some of the 'more entertaining' roads (25, 35, 45, 50, 60, 70, 80, 90, 100, 110kph) e.g. the winding Oxley Highway with its 300 corners.
Out of this plethora of limitations, 50kph is the only one which causes concern for me using the standard 18/36 gearing and on original size tyres.
50kph at 2,500 in 3rd on level ground on gentle throttle increments feels velvety smooth but any change in traffic conditions or if an incline appears, I immediately change down and 'awaken the beast within'; whereas 3,000 in 2nd at 50kph makes the engine 'surge'.
3rd, 4th & 5th have no problem sitting at 3,000 (or above) and feel wonderful!