PeterRB,
I can attest to weight/performance exceedance as daily occurrences and tree/foliage chopping as perhaps weekly. When life is at stake, and the mission is a tough one, the machine is a tool, and you use it to the absolute edge of its capability.
The Cobras I flew (AH-1G with T53-L13 engines) were MGW at 9500 pounds. I was the unit IP, and once did a weight and balance on each of the 9 aircraft we had (6 flyable any given day). The lightest one on the flightline, mission ready with crew, was 10,700 pounds with 1200 pounds of gas on board (about 2 hours to burnout, standard for our unit.) I went to the unit commander, and told him we had to fix this. He told me to do it, and just let him know what I left out, "the bullets or the gas!" Naturally, the issue stopped there. We changed rotor heads every 300 hours (2 months) and engines at about the same rate. The typical performance limited hover was less than 6 inches at initial takeoff. On a windless day over dirt, we had to bounce the aircraft to get through translational lift, which took about 100 yards of skipping and thumping. Once at a refuel point called Hawk Hill in I corps, I nearly clipped the barbed wire concertina that was 150 yards down a slight hill during takeoff, the wire was a standard roll, perhaps 30 inches in diameter. 30 inches altitude in 150 yards!
Cutting down small trees and brush were not done daily, but if a unit was in distress and that was what the AC saw on short final, having already made the approach (short final before the hover was the most exposed part of the landing) you MUST pick up the guys, or they might shoot you down if you chickened out. The Huey blades had stout aluminum spars and were capable of taking down a 2 inch branch with relatively cosmetic damage, maybe a wrinkle on the abrasion strip, and more often a tear on the skin below and aft of the strip. Those blades were changed that night, and ended up as bar rails at the club, or walkways to the latrine and showers. Some units could pave the area around the maintenance shed with old blades, literally. Too bad I didn't know to buy Bell stock then!
The rule that we followed was something the the military has forgotten in this period of unrelenting semi-war on the cheap, it was the same rule the air forces used in WWII. If the machine brought you home, that was enough, period. The bombs you dropped and the gas you burned were gone, too, so if the machine had to be used up like a pair of flashlight batteries, too bad. The service knew it, and expected it, the mission was everything. In the battle of Britain, the RAF ended the battle with more fighters than they started with, (but far fewer pilots) so machine was merely a tool.
A landing craft was worth 5 trips to the beach, max. A Spitfire engine in the Battle of Britain was tossed at 10 hours. A B-17 was routinely flown at 20% over max gross weight, and tossed at 10 to 20 missions, if it made it that far. My fathers unit, the 94th BG at Bury St. Edmunds, Norwich, launched 25 bombers on a typical maximum effort mission, and lost about 273 Fortresses during the war. That means that in 2 years, the unit was entirely wiped out and reformed more than 10 times!
Sacrifice in war should start with the machine, and then maybe go to the crew, as a last resort.