In an attempt to catalogue ‘effort versus style’ I’ve drawn the same elephant in different styles, in order of effort. In this illustration a sketch is the easiest and takes the least effort, while a digital painting is a lot more effort.
Still, in some cases lineart requires more work then a digital painting. It depends on how detailed and clean the lineart needs to be.
I’m capable of more styles then these four (or technically three if you don’t count the coloured lineart). But this illustration is meant to simply show the difference.