So I started allergy shots about 3 weeks ago (actually just leaving to
get one in a few minutes). On Aetna, I get alerts when the doctor's
office submits something for payment.

My plan covers 90% of the cost of the injections - not bad. That means
twice a week, it costs me about $1.70 for the injection for the day.

I wondered how this would be collected; but it looks like the doctor's
office submits something every time I go in. I get an electronic
notification via e-mail at work, and I had a look.

They're not grouped together. They send it in every time. I'm waiting
to see the first bill for $1.70 - I imagine it probably costs them $10 or
more to process the billing, so if they send a bill out for every
injection, the insurance company is definitely losing money.

I'm hoping it's not the case that they send a bill for every trip, but
hey, I get the same Visa Business invite about 3 times a week, so what do
I know? ;-)