Should I do all the recommendations at once?

This answer depends on how old your page is and where you are currently ranking. Generally speaking, the better you are ranking the fewer tweaks you want to make. If you are ranking well for a term, you want to only do a handful of tweaks at a time. If a tweak negatively affects your rank, you will know what to put back.

Even if you aren’t ranking well or the page is relatively new, a good strategy for those starting out in SEO or new to POP is called “climbing the ladder.” The concept is simple. First, do enough On Page SEO to appear in the top 100 Google results. If using the Content Brief, you will usually get inside the top 100 with a score around 75%. Once in the top 100, do your tweaks in small batches so that you do enough to move up a rung on the ladder (move up a little bit in ranking). Once you have moved up, do the next set of tweaks. Once you get more comfortable with SEO or using POP’s recommendations you will get a feel for the rungs you can skip and how aggressive you can get in your SEO work.