I see a lot of instructions and guides for resolving unconfirmed transactions that say that Rebroadcasting doesn't actually help and you should Reattach instead. So when should you Rebroadcast? Are there any specific symptoms that would indicate that my neighbors didn't hear me the first time?
Rebroadcast is only useful if there is a transaction that was seen by the node you are connected to (otherwise you don't have a button to rebroadcast), but was not seen by the rest of the network.
So unless you are using your own full node and know that a transaction was not broadcast, there is little use for Rebroadcast (Probably if you check multiple tangle explorers after a while after sending the transaction and it only appears on one of them, you might Rebroadcast too).