Some doctors do a dating ultrasound in the first appointment around 6-8 weeks.
The NT scan around 13 weeks includes another ultrasound (my doctor used this as the dating ultrasound).
And the anatomy scan at 20 weeks.
Some doctors may do a quick ultrasound around 35-36 weeks to check position, but it's not common.
If not for some growth concerns, I would have only had 2 ultrasounds this time around (NT and anatomy). My first pregnancy only had 2 (dating & anatomy). My second pregnancy had 3 (dating, anatomy, and quick peek for position), but I had to request the anatomy scan and was sent to another doctor.