Its important to remember that the various techniques which are known, and taught, were developed out of need first, then packaged and taught as a "technique" to newer pilots. There are many instances where a "tribal knowledge" technique is very common in the tribe, but never taught in pilot training or described in flight manuals. An example of this would be rolling one float out of the water first during a floatplane takeoff to reduce distance on the water.
Pilots who went before us simply figured out how to do what they needed to do. As aircraft manufacturers competed for customers, they caught on to the need, tested their aircraft, and documented and marketed their aircraft to make the most out of certain capabilities. I've never looked in a Piper Tomahawk flight manual for the soft field technique, but from considerable experience flying one out of a small grass runway, I can tell you, that there really isn't much capability there for that -but that's not what the Tomahawk was designed to do in the first place!
When you look carefully in flight manuals, you may see a technique briefly described, but no supporting performance data, because the conditions and technique are just too variable to detail in performance charts. On the reverse side, aircraft changes (like STOL kits) can enable much better performance than the manual describes. During a recent flight with an instructor friend of mine, I demonstrated in my STOL C150M getting airborne with she and I and 3/4 tanks, at 35 MPH, and steadily accellerating and climbing away (though slowly). I repeated this type of takeoff two weeks later by myself, while leaving my home runway, which was covered in 6 inches of crusty snow. It took near full power to get the plane moving at all, but the ground roll in still air was just over 400 feet (tracks in the snow measured against my runway lights). I had expected to use most of the runway. Accellerating to a typical 60 MPH rotation speed would have been hopeless.
It is my opinion that there is no excuse for these techniques not being trained and practiced with some frequency (along with stalls and spins, but that's another thread!). The next time you're flying, whatever you fly, and conditions are suitable, read the manual, and employ the technique described. You will find that you gain skill, and a feel for aircraft in general. Then when you happen onto a gravel runway, or foolishly land on grass in the spring, without first enquiring about its firmness, there is a better chance you'll handle the situation as well as possible.
I pay for the maintenance of my plane, including the propeller, and nose strut. Every takeoff has my nosewheel light, and off the surface as early in the takeoff as possible. In 23 years, I have never nicked my prop, or slammed my nosewheel. It keeps repair costs down!
I once employed a soft filed technique to taxi out a 172 to the runway. It had been hangered for some time, and I suppose forgotten, as they ploughed up the field between where it sat in the hangar, and the runway. With a soft field technique (and the owner and his daughter (of perfect mass) sitting in the back for ballast), I was able to taxi the aircraft out 500 feet, slowly picking my way around the big lumps, with the nosewheel never touching the surface. it worked just fine, and we flew out minutes later. You never know when you may need a trick up your sleeve, may as well practice!