Is it worth learning the Planck law to use a blackbody?

No need for you to learn the Planck’s law by heart!
However it is good to know some important properties of blackbodies as consequences of the Planck’s law:

Planck's law
  • For any given wavelength, the Radiance level is an increasing function of the temperature,
  • For any given temperature, the Spectral Radiance curve reaches a maximum which wavelength can be easily calculated from the easy-to-remember Wien’s law
Wien's law

Example: a blackbody at 800K (i.e. 527°C approx.) emits its maximum radiation at about 3.6 µm, i.e. in the MWIR spectral range.