The time to be realistic is now. People are not reading 3000 or 5000 words post anymore like before. This is the era where as a blogger writer you have to go straight to the point now days.
Of course you can still write long posts and of course they can get a lot of traction depending on the topic or your niche.
Writing is all about mainly finding your own independent voice, as you may have read already. In my case, for instance, I’ll continue experimenting with short posts and see where it will take me.