If the logic of the business is undocumented, the workflows are improvised, and the value depends on one person remembering how everything works, then what looks strong is actually fragile. Reducing owner dependence is one of the highest-return things you can do before a sale.
Practical steps include moving recurring decisions into written procedures, cross-training staff so no single person is irreplaceable, and separating your personal relationships from the business relationships wherever possible. The test is straightforward: if you stepped away for a month, what would break, and what would keep running on its own?
Every dependency you remove is a discount you avoid at the negotiating table. See What buyers actually pay for.