It is true that we use the same job description constantly, but we hire continuously too. Our team is mostly made up of full-stack Rails developers and so the same job listing has worked for many years as we have grown the team.
Reading every cover letter and resume we get takes a lot(!!!) of time. We only list open positions that we are hiring for.
"we're looking for someone that can hit the ground running!" has job open for 6 months, when they could have just trained an already skilled new hire