What is clause 60.1(8) specifically intended to pick up that clause 60.1(1) would already cover? If the Project Manager changes a decision that changes the Works Information then this would be covered by 60.1(1). So what examples are there of the kind of thing that would be picked up by 60.1(8) such that it was necessary to include within the contract?
You could look at the PM deciding that the works do not meet the condition for a key date and then changing that decision (clause 25.3) or perhaps changing a decision on the date for Completion (clause 30.2). These both specifically refer to decisions of the PM. However, I think for 60.1(8) you are looking more broadly than a contractually specified “decision” and looking at any time the PM makes a decision in the normal English sense of the word.