Whetstones require perfectly straight surfaces. The best option is regular using flattening stone after each sharpening. The stones will always be in perfect condition, and there will be no need for long alignment if this is not done.
Flattening stones have a lower grit of 100-200 and have deep cuts on the surface. The incisions prevent sticking to the whetstone. The easiest way to use the stone for leveling is to soak it in water for a few minutes, do the same with the sharpening stone and additionally draw an X mark on its surface with a pencil, when we wipe off the entire symbol, it means that the stone has straight surfaces.