The first set I use with counter and attack tactics, and the second with control and defend tactics. So far, so good. I just started a save with Leeds, made a 4-1-3-2 DM Narrow formation, very fluid attack, and added the penetration set, and am currently first in league...
I also found out I can play versus cup against myself, even though it's an online game. So I usually pick chelsea and manc and test one tactic against another. Funniest one was chelsea using counter, and manc using attack, which ended 9-6 for chelsea
Well, look at it this way: You may get better results if you adapt to opposition. You also may get worse results, because your team isn't adept at playing out the new instructions. It both has it's pro's and con's. You may get a major win, or you may lose, it's a gamble. Opponent, well, perhaps not AI, can also adapt to you.
Well, basically, there is no "hold lead" as such. It's just a matter of how much you are willing to risk to score and how quality the chance will be. Obviously, if you play possession, you will have less shots, but more on target, possbily ccc, so it may be useful to increase risk by increasing mentality. The more you risk, the more the probability is of goals being scored, on both sides. So an attack mentality with penetration set would probably score and conceede most goals, while defend mentality with possession set would probably end up a 0-0 match. It's a matter of fine tunning. I beleive you would have best combo with perhaps control mentality and possession set, or counter mentality with penetration set, depending on your players.
A basic 4-4-2 to start against all opposition
An attacking formation for when I feel like its against an easy defensively weak opposition (cup games)
A defensive formation against the bigger teams in the league or when holding an important lead
Ill try it out in my online game and let you know how I get on.