Why frigates were not disposable warships

Were early frigates considered cheap and disposable?

No. A wooden warship represented too much skilled labor and material to be disposable, and a well-built hull could serve for decades through major rebuilds.

Ships built from unseasoned or soft wood could be cheaper and short-lived, but seasoned hardwood warships were major investments. Even frigates might remain in service for a very long time, although a century-long career could conceal extensive rebuilding. Smaller size therefore did not make an age-of-sail warship expendable.