> i mean it's nice to get a response as soon as possible but this seems completely unrealistic

If you run recruiting like it is important, making sure recruiters and hiring managers have the tools and time to talk to candidates quickly is really easy to do. A lot of companies run recruiting like it's a surprise when they have to hire or view it as less important than other functions... and then put lines like "our people are our greatest assets" on their careers page.

Most people who respond to job ads are actively searching for jobs, they usually apply to multiple places simultaneously. If the other places responded quickly then, by the time you responded in a few days, the applicant could be far along the interviewing with several others and might not be considering your vacancy any more or prioritize it after everything else already in the pipeline. If you responded in a few weeks, the applicant might already have taken an offer.

If a customer rang would you pick up the phone right away?

Why not treat your potential staff as more important than any of your customers?

Which is harder to acquire? Customers or Staff?

> Which is harder to acquire? Customers or Staff?

Customers. By far.

weeks would drag the application out for months though