The old '06 IS probably the finest "all around" caliber ever developed. It wasn't developed to be that. It's just how it all eventually worked out. I believe Elanor O'Connor shot her lion with the '06 and 220 gr. bullets way back when. It's also been used on buff and elephants and rhino when folks got caught in a bad situation unexpectedly, and it was all they HAD to "fight" with. However, it DOES also represent about the maximum limit many folks can tolerate on the recoil end of it. I don't know how many guys I've known who missed a deer, and said it wasn't enough, got a .300 mag., and were afraid to pull the trigger on it. Many of them never hit a deer with it because they jerked the trigger, and missed even WORSE than they had with an '06. We seem to be becoming progressively less tolerant of recoil, but in an 8 lb. sporter, with a pad, it ought to be tolerable by most shooters who are willing to learn the discipline necessary to overcome their fears of recoil. Muzzle blast is also a factor in perception of recoil, and many react more to that than the actual recoil. Most of those insist on shooting without muffs - a very foolish and far too "macho" situation!
But many have put forth the precept that accuracy is NOT a function of caliber, but of the rifle's fit and the precision with which it's built. Square and concentric chambers are always an asset. Throat dimensions can be a factor. But mostly, accuracy is just a function and result of all the care and precision built into the gun by the 'smith who does the work. It's that extra precision and detail work that makes "real" target rifles so much more expensive and accurate than off-the-shelf sporters made en masse for the average shooter. The loads you feed it, and their OAL and other specs, also play into the equation, and it takes some actual shooting to find out what your own, personal, individual rifle wants in order to shoot its best. There are some general guidelines, like neck sizing cases where possible, charge wt. and specific bullet and its jump to the rifling (if any), etc., etc., etc.
There's a reason the same shooters tend to always find their names at or near the top in matches, and mostly, it's really just a matter of how they manage the details - the "little things" that many are too impatient to attend to - that makes them so consistently at or near the top of the winners' lists. Accuracy is a goal, not a destination. Its pursuit will always be tenuous. I've seen many who just selected some arbitrary load, shot it, and if it didn't shoot, blamed the rifle. That's not how one finds accuracy, usually. It's found by first off, getting as well made a rifle as one can afford, and it's quite surprising how off-the-shelf guns perform with a little knowledgeable experimenting. I've seen them shoot 3/8" groups for FIVE shots, and do it consistently. 5/8" isn't uncommon IF the shooter works up his loads properly and tests various bullets. Sub-MOA is common. BUT .... you DO have to develop your loads to match what your rifle likes. It's all "hard work," at least in the mind of most today. I always looked at it as fun and interesting, and an excuse to shoot more, and learn something from it - at least for that particular rifle. I once found that Hornady Light Magnums in 150 gr. shot better than my traditional loads - a very embarassing situation! But its throat was pretty worn, and I rebarreled it. Now, it'll shoot like it's got eyes! Still an '06, but with a Shilen barrel now.
Accuracy is always going to be a goal, and one that can be elusive unless we learn a good bit about what causes it to be enhanced in most rifles. And even then, you'll encounter some that will defy the "rules," and want something you'd never have expected to shoot its best. If anyone has ever figured out why this is, let me know. I've heard theories, but no real "answers." Testing on target will always be the ONLY way to establish what a rifle will shoot, and what it doesn't particularly like. And that's just how it is, unless someone has found a better way.