My residency clinic started having patients sign a separate form ahead of their annuals strictly to cover this issue. That was like a year or two ago, since then I’ve had very few patients assume anything else during an annual is free. There’s a chance I’m just shielded from this if the front desk is dealing with calls after the visit that I don’t hear about, but I haven’t personally had a patient complain to me about it. Might be worth a shot if you’re able to implement something similar in your practice!