Maintenance is easier to value when it is described as a set of outcomes: the site stays supported, recoverable, monitored, and usable. “We update plugins” is only one small part of that responsibility.
A sensible plan
Include version updates, backup checks, security review, uptime monitoring, key-page and form testing, performance checks, and a record of changes. Decide how urgent issues are reported and what response time is realistic.
Match the plan to the site
A brochure site with no integrations needs a different routine from a site with payments, memberships, a CRM, or custom plugin code. Review the plan when the business adds a new dependency.
See the WordPress maintenance service for a practical conversation about coverage and ownership.