Nope, nothing out of the ordinary.
As people pointed out, IF you're in Bangkok (or Chiang Mai) make an appointment as you don't need to do anything but get there about 15 minutes before your appointment.
Also remember IF you're using banked money method MANY offices are requiring you have a years worth of transaction history printed out. That is to prove you kept 800K baht in your account 3 months after the extension was granted and then the balance never went below 400K baht for the rest of the year. Also the legal requirement is that the 800K baht be in your account for 2 months BEFORE you apply for your new extension (so if an immigration office is saying it's 3 months they're wrong).
In Chiang Mai you can apply for your new extension when you have 45 days or less left on your current one and you don't lose any time going early because they add the new extension to your expiration date.
Here's the website of the Chiang Mai appointment booking;
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