I recently had the pleasure of working with a recruiter from out of the area who was looking for a dozen temporary employees. We reviewed many resumes and, big surprise, many were bad. Not terrible, but difficult to follow. For a lot of them, it seemed all of the right info was there, it was just poorly arranged. This type of resume lists experiences apart from the jobs where those experiences happened.
Most "experts" call this type of resume "functional".
Trust me. Functional is anything but functional. Catchy name. It's supposed to highlight the work you've done. But if it's harder for the reader to follow, how functional is that?
Ninety percent of resumes (and 100% of the ones I reviewed recently) would be more effective if the writer ditched the functional format in favor of the traditional reverse chronological format.
WHERE and WHEN you did the work (the context) is as important as the fact THAT you did the work. With a functional resume, you can easily hide the fact you have only one month of experience in a skill that is important to the hiring manager. That means, even if you have nothing to hide, it's still a red flag.
Remember, you want the hiring manager to visualize you doing the work. It's easier to do that if they can see the company name in their mind.