Don't the ULCCs fly to KTM (from KUL or BKK, I can't remember which)? Maybe u get lucky and roll a strike straight through, but often you can get those dilemmas where it's 50K extra miles or the 2 tickets with the LCC flight with someone like Air Asia.

When I did my trip I think I booked it SIN-KTM-SIN on SQ using UA miles. Dunno what they want for that now.

Would imagine that much also depends on time of year and supply/demand. KTM is very seasonal, with short peak seasons. October is always high demand but has the best weather and views. I went in the second best time in the March/April window, when you had maybe 4 or 5 morning hours around Pokhara before clouds rolled in.