though personally I've never done this directly, as this is usually the job of a library that handles that particular data format.

Ah, yes, the luxuries of modern desktop computing. I grew up with Commodore computers (VIC20, C64, Amiga), and nowadays i sometimes work with Microcontrollers of the Arduino family. When you are low on memory (="always"), you tend to code as low level as possible.

Heck, for one of my projects i'm talking to the memory chips directly via I2C, because the corresponding library would require ~200(!!!!!) bytes of RAM. When you only got 2048 of those buggers in total, you tend to turn into Scrooge McDuck.

But even in some of my more recent data extraction projects i had to use random access for fixed size records.