The GP is correct in many cases. Part of the reason Eevee was created was for this exact purpose. You can't preview certain shader nodes (though you can preview most of them), and you can't preview raycast-only effects like indirect lighting (unless you bake it) and certain volumetric effects. But you can preview your geometry and direct lighting and physically-based materials well enough to get an idea of how things will look, and then you can make a final pass where you preview the actual Cycles output.
If you're fixing your UVs, or adjusting the depth of a bump effect, or arranging a scene to see how objects' colors balance with each other, or tweaking the metal-ness of a material, Eevee works great as a preview even if your final render will be in Cycles. Eevee is particularly useful when working on an isolated object (minimal indirect lighting), vs seeing how an entire scene gets lit.
If you're fixing your UVs, or adjusting the depth of a bump effect, or arranging a scene to see how objects' colors balance with each other, or tweaking the metal-ness of a material, Eevee works great as a preview even if your final render will be in Cycles. Eevee is particularly useful when working on an isolated object (minimal indirect lighting), vs seeing how an entire scene gets lit.