I never say "objection". I have also never heard it done. But I WILL object if my opponent leads the witness in chief when it has not been agreed he can do so, attempts to give evidence himself, introduces hearsay that has not previously been agreed, making comments instead of asking questions or steps outside of relevant issues. There is no "list" - sometimes you will need to intervene if the advocate is being unnecessarily difficult and not allowing the witness to answer the questions, or phrasing the questions in such a way that they are incapable of understanding (particularly with child witnesses). Generally, there are a few niggly bits, but every now and again, you end up objecting to practically everything your opponent says (in one locally famous hearing, my opponent objected to my objections, just a fekkin shame that he spent the whole of his cross examination attempting to give evidence himself!)