No, you shouldn't need to.
Do you have other Conditional Formatting rules in play?
NO
Do you have calculation mode set to Automatic?
UNSURE, where is setting at?
If you are applying this formula over a large range, how exactly are you extending it to cover that range?
DRAGGING
And as Fluff asked, are you doing this in Excel or some other program/app?
GOOGLE SHEETS, sorry I forgot to mention this.
I suggest that you update your
Account details (or click your user name at the top right of the forum) so helpers always know what Excel version(s) & platform(s) you are using as the best solution often varies by version. (Don’t forget to scroll down & ‘Save’)