I never find a use for Deep Vigor when mining. The only case were I saw it have an effect was in leves where the chance of getting an item was not 100%. And Deep Vigor only works after chain 4. For some reason a lot of the leves stuff for mining allows you to gather up to six items per node.

In real gathering though, I can have a 100% chance of getting everything from the node. I get to chain 4 (with some nodes), and Deep Vigor highlights but the node is mined out. So I see no practical use of Deep Vigor other than assuring you can finish you winning streak (if you had one) on nodes in a mining leve.

Maybe someone else knows of a practical use for Deep Vigor besides leves?