As many readers might be aware, I started tournament play at age 16 as a really terrible player. It was not until my fourth tournament, after 8 months of play, that I won more than one game in an event. However, once I learned how to play "Real Chess" (although I did not call it that at the time), I improved very quickly and, less than a year later, I had my USCF rating up to about 1700.
In those days sudden death time controls (all moves in a given time) were illegal, so games could drag on for many hours and often had to be adjudicated or adjourned.
One day I was playing in a tournament and woke up early to take the train to downtown Philadelphia for the event. In the morning round I got paired with a player rated 100-200 points higher than my 1700 rating, and the game dragged on for several hours. I played very carefully on each and every move (an idea one of my students has deemed "WEM" chess - Work Every Move, which is certainly similar to the thought process Real Chess, although a slightly different dimension...)
After a quick meal I got paired with another similarly higher rated player and proceeded to WEM/Real my way through several more hours of close play, taking me well into the night. I think the train I managed to catch home left the downtown station about 11 PM for about a 50 minute ride home. I was only 17 years old, but completely exhausted. I had done well in those two games, but was it worth it?
So, while sitting in the passenger car staring out into the darkness, I posed myself a key question: "Did I really have to work that hard and be that exhausted?" Now that I knew what it took to fight on every move and begin to play with the big boys, wasn't that enough? Perhaps I could spare the body a little and let up once in a while. I bet myself I could still play about a respectable 1800 without killing myself, and that might be a good tradeoff. Should I take that route?
My decision took about 30 seconds: If you want to do something, do it right. Now that I knew what it took, I couldn't look myself in the mirror if I would make a move - any move - without trying my best, given the position and the time control situation (something I call Micro Time Management). So, I resolved that whenever I would make a move in the future, I would always try my best; if I did not feel like thinking a long time on a move, I would play a shorter time control. However, no matter what the time control, I would always try to use almost all my time each game (assuming it remained competitive and lasted the distance), and do the right things as best I could on each move.
It was the only answer I could live with. That was about 45 years ago and it hasn't been that hard to keep my promise to myself. In fact, if I had decided otherwise, it would have been very difficult to play less than my best at any time...
Look at it this way: Suppose an 1800 player lets up for one or two moves every game and plays like an 800 on those moves. What would his rating be? Probably about 1500?! So, the next time you run into a 1500 who tells you he is just as good as those 1800's, it is possible he is telling the truth, with the caveat that for whatever reason - lack of concentration, laziness, tiredness, whatever - he may not be able to do it every move of the game. That's maybe (just maybe - it could be lots of other things) the one skill that 1800 may have that the 1500 doesn't. And, make no mistake, that is a skill, or trait, or whatever you want to call it. It only takes one bad move to throw away a game.
You want to be good? Do everything in your power to make sure that the next move you make is not the one that throws it away. Doing so may not make you a good player but, as I summarized at the end of The Secrets to Real Chess, not doing so will almost surely prevent you from being one.