Getting the first records out of a customer's system takes a capable engineer an afternoon. The cost comes in the months after: credentials expire, a schema changes without notice, an incremental load quietly stops picking up deletions.
Each integration becomes a small application with its own deployment, logging and failure modes, and usually one person who understands it. Ship a dozen and maintenance, not build cost, caps how many customers you can onboard.
We keep the customer-specific part explicit: how the source is accessed, the field and value mappings, the rules for that account. Credentials, scheduling, raw data retention, incremental state, validation, deployment and versioning come from the platform, the same for every integration we run.
Start with one source, one destination and one integration. You judge a real production result before committing to anything larger.