Whenever I go to the dealer, they always recommend a manual brake adjustment for $120 every 7500 miles. Is this actually necessary? And can I do this myself? They also recommend changing brake fluid every 15k which I know is complete bs.

 

Really easy to do.

On 2009 and later years, the Maxima changed from a handbrake emergency brake lever in the center console to a foot pedal press to set-press to release emergency parking brake.

To adjust the parking brake, just press the parking brake pedal down slightly and lie on your back and look under the dash. At the very end of the parking brake foot pedal linkage closest to the dash panel you'll see a 10mm nut on a long screw that is turned to make the adjustment. A long 10mm socket or a 10mm box end wrench does the trick. Only takes about 3-4 turns clockwise looking up at the nut to restore the parking brake due to cable slack or stretch

 

^ that is if the adjustment is needed there.
The shoes can also be adjusted inside the rear brake hat to tighten the parking brake.

Not needed generally.

A brake fluid flush every year, or 15k on average, is not a terrible idea.
The fluid attracts water, which can boil and kill your brakes under hard use, and the moisture can damage the internals of the abs control pump/module.

 

So it sounds like this manual brake adjustment is for the parking brake and does not have anything to do with normal braking performance?

 

That is correct.