Is it “all” or “all of”?
In most cases, we forgo the preposition “of”. The time when you would use “of” is when it is followed by a pronoun or in the partitive of phrases.
Where you would normally dispense the preposition "of":
All (of) my hard work just went down the drain.
All that suffering is so unbearable.
All (of) his past continues to haunt him.
All John’s paintings were sold out on the first day of the auction.
Where you would keep the preposition "of " as in the partitive of phrases:
All of that block of business will be transferred to our vendor.
All of these mountains of information is unreadable.
Where you would keep the preposition "of " as followed by a pronoun:
All of us decided to stay in Colorado for the winter.
I can't stand all of you following me around.