My two most common instructional situations caused me to have a horizontal more than vertical orientation: Teaching in very low powered airplanes at very high density altitude airports all day rather than just morning and teaching crop dusting.
I had to develop my own syllabus for these situations because FAA approved ones and the one most pilots and myself had been taught under had a vertical orientation. POH and takeoff criteria were mathematically established and neither takeoff near ceiling nor overloaded were considered. Takeoff near ceiling and/or overloaded require horizontal orientation.
Takeoff from a high MSL airport in the heat of the day requires at least a thorough map recon and hopefully more intimate knowledge of the terrain, especially how the snow melt and rain drains from the area. We need to be aware of any slope in our runway and wind speed and direction. We need to know where we might best expect orographic lift soonest down drainage. Downslope on the runway and down drainage are generally our best horizontal directional choice as we may not have sufficient engine thrust to takeoff upslope and climb up drainage to the nearest potential orographic lift. Zoom reserve in the form of airspeed developed in low ground effect may make clearance of obstructions possible, but rudder turns in ground effect may be more reliable and airspeed will bleed off in a zoom climb possibly requiring level or down hill flight beyond the obstruction.
Having done the math, we may determine that the horizontal considerations of the last paragraph are not necessary, but once we leave ground effect, climb, and turn up drainage we are committed to a vertical orientation until a hole can be found for a descending turn back down drainage.
As a crop duster, the load is all that can be reasonably carried. If we can make it horizontally to the field, however, we know we can lose some weight in the first pass or two. We are concerned with enroute obstructions we can neither rudder turn around nor go under. You guys that fed the villages up north and hauled the natives had no way to lighten the load part way through the mission. Also, you had low ceiling much of the time. Yours, I would think, was a horizontal orientation much of the time.