Usually you want way more solution in the syringe than needed to help you clear any air bubbles (that would be a Bad Thing)- but you don't want to overdose either - so the excess is dumped. You're not paying for it.

Which reminds me ... with this crazy volume of shots ... I would worry about some n00b "nurse" screwing up the basics more than about the actual stuff. Sure "anybody can do it" .. that's exactly the problem.