Some things were mentioned in the thread I linked to (perhaps this one can be merged with it?):
- a 3rd+ ID can make the community ID more secure in case of ignorant/malicious future IDs, or if the account (and associated IDs) of one of the earlier identifiers is deleted
- reviewing Research Grade observations is helpful for finding misidentifications
- the person doing the identifying is engaging with the observation and the iNat community
- it boosts the identifier’s ID count
- the identifier can add annotations at the same time while going through the observations, adding new information
However, the cons (especially for 5-8+ confirming IDs of a species that is easy to ID) are:
- it’s extremely frustrating to overturn the community ID if all those identifiers were wrong (please help with Ferald and Berald, but make sure you know how to distinguish the relevant species ;) )
- time and effort could be better spent identifying Needs ID observations (e.g. Unknowns, underidentified taxa such as insects) rather than redundant IDs on RG obs
- an identifier who identifies thousands of obs of easy-to-ID species will show up high on the ID leaderboards, implying expertise
- it can spam observers with notifications
So while it’s definitely not wrong, and there are some benefits, the general consensus seems to be that it can be frustrating and generally not super helpful.