All interesting posts. Human nature is at play with the thoughts of 'if I don't/can't do' it then it is unethical has been played out endlessly here and on other forums when the subject comes up.
So it goes like this, decades ago the rifle was sighted in for 3" high at 100 yards, a long shot in the field was 300 hundred yards, but the majority of shots/kills came at 150 yards average. Didn't have to pass on too many animals because of long / unknown ranges. Practice was the sight in , annually, then offhand shooting at rocks and things at varying distances but usually not more than 200 hundred yards.
This worked great, my rifle would put 3 shots into 1.5" at 100 yards, bagged a lot of animals. This seemed the standard and probably still so.
With the availability of 1000 and 1500 yard ranges in my area, an opportunity became realized, not stuck to 200 or 300 yards anymore.
Quickly found out with the 1970's tools I was using did not make the grade, Rem 700 BDL, 6x Leupold scope, handloads that went bang! The standard of the day for any savvy hunter....and a 7mag to boot, cutting edge in all respects.
Practicing at long range at first was very frustrating as hits were not coming like on TV.
Undeterred, things began to change. First 1000 yard competition taught me my handloads sucked, no small effort in expense and education fixed that.
Next was the scopes I was using did not dial correctly so you were always working with a fudge factor and even then they were not always linear in adjustment, some expensive scopes would not hold zero enough for small groups at distance,
next thing is the patterns of the 5 and 10 shot groups, tracked that down to bedding the barreled action in the stock.
Still in progress here, the things I am working on now is environmental factors, wind is big, as is mirage and available lighting.
At the range there is an IPSC target (steel T-shirt) set up at 1160 yards, the idea here is a first round of the day hit on that target. It has only happened once, second round hits are more reliable, but not good enough. Once your 'on the wind' then this target can be connected 9/10 times (in relatively quick succession) being my best ,as wind twitches around....mountainous terrain.
My primary hunting tool is a Sako 30-06, using 200gn NAB's at 2690 ft/s, zeroed at 219 yards. Scope is a SWFA 6x Moa /Quad.
This set up is reliable to at least 540 yards in the field.
Conditions would have to be perfect to go beyond that with any rifle, considering my personal skill level as of today.
Shooting at 1000+ yards brings a lot of humility with it.