The length of time an integration can take to sync varies across platforms.
Some integrations return a list of IDs, requiring us to make N requests for all objects, resulting in a longer sync time. Data can be pulled through a list endpoint for other platforms, so the sync time is significantly shorter!
Another factor that affects sync duration is the volume of data being pulled from the platform. Some integrations will have millions of rows of data, while others will have only a few hundred. If you're linking an account you know has a large amount of data, you should expect longer sync times.
Additionally, the type of sync will also change sync times dramatically:
Initial Syncs - All initial syncs (i.e., when the account is first connected) will take significantly longer than subsequent syncs because Merge pulls all data available in a platform
Subsequent Syncs - For most third-party platforms, all subsequent syncs only pull changes since the last sync. This means sync times will be dramatically lower than an initial sync and usually just a few seconds long.