I play and test Narrow Diamond all the time and I have to change arrows and orders to succeed against different teams. I am seriously interested about your Red arrows on you DL/DR, quite brilliant but I was skeptical about it usefulness against 4-5-1V, 3N-5-2V and especailly against 3W-5-2V!
Yes you can end up playing all your friends every season, season after season, just wondering if you face about the same teams every season?
I un-friend everyone at my level at the end of the season so that I will not have to face them next season, they are all very good manager and all watch each others games. I do not need the challenge of very hard league as I like to focus on the CUP and CL too. I will pick up my friends on the same level through out the next season whilst watching mutual friends games.
Good Luck with your 'never changing tactics'... I personally have to change my ND, all day long because I play different crazy formation teams all season long.