You’d be surprised. I’ve worked with some even pretty large companies that just don’t have a good process for this and rely on people doing some semi-manual process to prepare a response. My current employer got swamped with requests unexpectedly and had a hard time dealing with them all.

Interestingly finding them was the hardest part because requests can come in to any part of your business, even via social media: https://ico.org.uk/for-organisations/uk-gdpr-guidance-and-resources/individual-rights/right-of-access/how-do-we-recognise-a-subject-access-request-sar/#socialmedia