Knitting in the round when the pattern says otherwise

I have a theoretical “how to” question.

Say, for example, I find a very simple vest pattern in stockinette. The pattern, however, calls for the front and back to be knitted up seperately, then seamed together.

If I want to get “adventurous” and knit the vest in the round up to where it seperates for the armholes, do I just add the stitches from the front and the back together and start knitting away? Then follow the instructions on the pattern for the front and back as they are stated?

I of course realize that if there is any kind of fancy stitch happening here that I have to read the instructions different since I am on the right side of my project only. Right now I’m thinking purely of a simple piece in stockinette in one color.