Well, it all depends. For most modern rounds, at least for hunting purposes, I will load up to the gun's max load, which may, or may not be more, or less than book loads.
However, certainc artridges from days gone by are not loaded by the factories to their full potential, nor do the loading manuals give data reaching the rounds full potential, so what to do?
The .257 Robt. and 7x57MM were found in weak 1893 and 1895 Mausers rated to 45,000 P.S.I. Back then, they used the copper crusher method for determining pressure, so they should consider those P.S.I. readings as C.U.P. numbers as they do now. The 30-06 is another cartridge not loaded to it's full potention due to the weak low numbered Springfields. Even some of the relatively hot rounds have been downloaded due to their being used in pump and semi-automatic rifles. Check out the velocities of the .270 Win. just 15-20 years ago compared to what the round does today. Even the already downloaded 30-06 had had their loads reduced a bit more.
Now consider this, if you will. You buy two rifles from any current manufacturor, Ruger, Remington, Savage, or Winchester as examples. Rifle #1 is in .300 Win. mag. loaded to 65,000 PSI max and rifle #2 in 30-06 loaded to 50,000 PSI max. Does this mean that rifle #2 is made from inferior material? I don't think so. So, if rifle integrity is the same, by that materials of equal strngth, then why can't loads approaching the 60,000 PSI level not be used by a careful handloader? I'll answer that by saying, there is no reason why this cannot be done.
I'm sure you've read that the 7x57MM is inferior to Remington's 7mm-08. That's true, only if you stick to comparing factory ammo only. In a modern rifle, such as my Winchester Model 70 Featherweight, it's no problem reaching better than 2750 FPS safely with great accuracy. with a 140 gr. bullet. That's where I settled on for velocity, although I did work up to 2880 FPS which is faster by 30 FPS than one of Hornady's Light magnum loads. I did back off because I felt I might be reaching a pressure plateau that could be a problem, although case head measurements and chronograph data said otherwise.
It gets quite hot here in Arizona during the summer, usually somewhere between 100 and 115 degrees in the shade. This is the time frame when I work up my max loads for whatever rifle I think I'll be using during the hunting seasons. Any signs of excess pressure will show up much more quickly during this time of year.
It is my feeling that any load that I can safely use at 100 degres and higher should be perfectly safe come the cooler weather of hunting season.
BTW, check out the velocity specs for the .300 Win. mag. Sometime in the past few years it's been dropped by 100 FPS.
Another good round not loaded to it's full potential, the .280 Remington. Remington want it to be used in pump and semi-autos. In a good modern bolt action, the .280 can crowd on the 7MM Rem. Mag.'s heels witha 24" barel.
Now, with all that said, and remember, I qualified that by saying they were laods worked up for hunting, probably 80 percent or more of my shooting is done with cast bullets loaded to mid-range levels. Two of my favorites are about 190 gr. with 25.0 gr. of either 4895 in any brass for the .308 and 27.0 gr., same bullets in the 30-06, both loads doing about 1800 FPS. Accuracy is just fine with the .308 load averaging 1.5 MOA at 200 yards ans 2.5 MOA at three hundred yards. The 30-06 load will consisntanly knock down pig silhouettes at 300 meters as long as I do my part. I do use a one grain tuft of dacron pushed sown onto the powder charge to hold it in place. Bullet is usually Lyman's #311644 sized to .310".
So, to answer the question, yes, I load to max and beyond in appropriate cases (no pun intended) for hunting big game and mid range loads for sheer pleasure.
Sorry I was so long-winded. NOT!
Paul B.