Every monitor is different. You're going to have to find the ideal values on your own. If you don't have tools (hardware & software), you're going to find that your brain is going to fool you one too many times, and you'll end up with inaccurate colors.
It's very subjective though, a lot of people believe it or not, don't like to look at accurate colors, if given the chance. That's because they look almost flat, compared to oversaturated, so again, very subjective.
It's only a requirement if you're working with color sensitive projects, but even then, there are tools which can easily correct color for you in say an editor software.
The biggest mistake people make, is calibrate a display in x K degrees, then end up increasing or lowering the temperature, so what once was accurate, no longer is, that's called placebo.
All the best!