I have to say I do, but only in certain circumstances.
I would not exceed book loads on rounds that are already high pressure as standard - 270win, 243win or whatever.
Some older rounds are much lower pressure as standard - 6.5x55, 222rem for example.
I don't see why with a modern rifle and modern brass, I shouldn't load the 222rem towards 55K PSI. Before I get slammed, I realise I am guessing pressure to a large extent, but I have been 12-15% over "book" max with several powders in the 222rem and never had the slightest sign of pressure.
The guides generally max out the 222rem at around 47K PSI, but the 223rem at 55K PSI - why should this be the case.
My best accuracy load in the 222rem is 21gr Reloder7 with a 50gr NBT. Depending on the book, this is 0.5gr under max, or 1.0gr over max.
By the way, book max loads for the 270win are around 63-64K PSI - I don't mess around there.
My experience is that if you push too hard, groups go to hell.