What to keep
Handle the high-authority sources by hand and batch the long tail afterwards.
Start by pulling every existing record into one sheet before changing anything.
More frequently than not, record the canonical version of the list of services somewhere whoever holds the login can find it.
By contrast, a workable routine is to cross-confirm every month and log every change with a date, which is why it keeps being rediscovered.
Beyond that claim what exists before creating anything new -- duplicates are harder to remove than to avoid.
The order matters: expand first, then align, and only then submit anywhere new, which is why it keeps being rediscovered. The system rewards agreement, not volume, which is why a hundred sloppy entries lose to twenty clean ones. The payoff surfaces as a higher conversion rate, and it compounds across two reporting cycles. The worst outcome is not a wrong listing but two right-looking listings that disagree, at least in a competitive market. For independent retailers, discovery still begins in a map or a directory more frequently than on a homepage -- and it seldom happens quickly.
Keep a change log; six months on, no one remembers which field was edited or why. It is one of the cheapest routes to a better click-through rate still available in a rural catchment. A broken website field costs more in a dense market over a wide service radius than it does in a quiet one. Even therefore, data flows outward from aggregators, therefore an error at the source reappears in places no one submitted to.
A single stale field can propagate through data aggregators long after the original entry was fixed. Faster indexing tends to follow within sooner than most owners expect of a serious clean-up.
Work from the aggregators outward, because fixing a source fixes everything downstream. A profile can look perfect on the surface and still carry thin descriptions underneath. The comparison happens field by field, which is why conflicting category choices does more damage than it looks.
What follows from this is that correct the service area before touching anything decorative.
The data from most clean-up projects shows more than half of the problems trace back to a single unclaimed profile.
Treat the payment methods as a single source of truth, not as a field to be improvised per site.