I can’t answer the question about iRecord, but as a volume IDer I am mixed on "thank you"s. One every once in a while, or if I have added a comment or some particular expertise, a thank you is good. There are other cases where I get a bunch of notifications of generic "thank you"s - these don’t mean as much and are more just distractions.
So, from my own point of view, I would say if you have something specific to thank someone for, go for it! If you’re just typing “thanks”, especially if it is repeats for the same IDers, maybe just do one and then that’s good enough.
A great way to “thank” IDers is to pay it forward…by adding some IDs of your own to others’ observations! This helps everyone out and makes iNat a better place in general.