It’s true that you want to keep your writing as conversational as possible, but at the same time, you want to avoid mistakes that can lower the grade of what you produce.
No one wants to read Shakespeare on a regular basis, but at the same time no one wants to read sloppy writing because that’s just not engaging.
Writing like you talk might work for a corporate email, but it might be the kiss of death for your fiction or non fiction book – if it’s not well done.
One of the biggest mistakes I see self-published authors make is start a sentence with BUT or AND! See More . . .