'If and when' is not always redundant:
1) I will make your favourite breakfast if you finish your homework
2) I will make your favourite breakfast when you finish your homework
3) I will make your favourite breakfast if and when you finish your homework
(2) and (3) specify that the breakfast will be made immediately, or soon after, the homework is completed, whereas (1) doesn't indicate a time, suggesting it will be at the next opportunity (e.g. tomorrow morning).
(1) and (3) include some doubt as to whether the homework will be completed, whereas (2) assumes that it will be completed, and only the time is unknown.
>Removing it would change the statement to one of fact or make it prescriptive when it may be better taken as descriptive or a possibility among many.
There are better ways to make these distinctions, and in most contexts, you don't need to differentiate between facts and opinions on account of the difference being obvious. And where it isn't obvious, it's obviously debatable, and people will do that regardless of whether you make such a qualification.
Unfortunately it is not me who needs to differentiate, and many seem to blindly assume statements to be as fact, when they are meant to be as opinion.
I agree that it is a waste, but I can't change the way my words are perceived, only the words that I use.