I haven’t done any testing on this and I only have my system and common sense to go by. But here are my thoughts:
1. Yes. It is system dependent.
2. But aside from that I think that it may not matter that all your cables are of the same maker and the same series within their lineup.
3. But I do believe in the weakest link concept in that while your cables may be from different makers, they should all be of similar quality as your system (or my system) IMO, is only as good as the weakest link.
Have a good weekend.