[Fat Charlie]

Most vehicles rated below 4 tons aren't designed to haul loads well. They aren't even designed to haul groceries well. They're designed to appeal to focus groups with meaningless things like 0-60 times.

So yes, staying in the part of the band with the most power and climbing steadily through the gears will get your full load smoothly and safely to cruising speed. And because of herd mentality pushed by marketing demands, 2nd gear will take you up to or close to 60 mph: my little econobox will get to 50. Top gear should be a perfectly acceptable way to get from 50 or 60 up to whatever your desired cruising speed is unless you're loaded, on a hill or have some merging requirements. At which point, that's what all the other gears are for.

Automatics do the same thing, made even more pronounced if you engage their "eco" mode. Some manuals have even had a 1-4 skip "feature" to raise fuel economy. I haven't heard anything about it in more recent years, probably because the very few people who go out of their way to buy manuals resent an automatic system making gear decisions for them.