Why use a flag, when you can just use an ATTINY

[dannyf]

Good question. Answer is left to the reader.

That's a poor way of backing up your argument.

[zapta]

Good question. Answer is left to the reader.

That's a poor way of backing up your argument.

Nice bait.

[tszaboo]

Good question. Answer is left to the reader.

That's a poor way of backing up your argument.

Nice bait.

Expected from a troll.

[nctnico]

It means you have some stuff that really needs to be done at a specific time.

What happens when you want some stuff to be done while your processor is polling the switch?

Use a higher level interrupt! But still a microcontroller has only time to do X in Y time. So the amount of processing time to do all tasks should always be less. Using interrupts and DMA can be really helpfull but you have to plan resources usage in advance.