Yes, you have to do that. But I would recommend doing this only for the most important pages where you are expecting to generate search traffic. For filler content and slim content posts – I would recommend leaving them as they are.
Please note that updating posts without changing anything inside might get you penalized. Google might think you are trying to trick the “date” in the SERPs.
So, only edit posts when you are going to make some changes inside the content after following the recommendations given by RM.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.