That is one way to do it, and I have done that for certain technically challenges clients. It is quick and simple. It does add a query to the parent page, but that isn’t catastrophic. It would work fine if you have a few of these pages and aren’t adding or editing them a lot.
The second option is to created a custom post type and add ‘content-left”https://wordpress.stackexchange.com/”content-right’ classes as you loop through. Each iteration you’d have something like $myclass = ($myclass == 'content-left') ? 'content-right' : 'content-left'; and your stylesheet takes over from there. It is slightly more complicated to set up but ultimately will probably be better, especially if you have a lot of posts. Managing Pages gets to be a pain, in my opinion, if you have a lot of them.