1. for 4-1-2-1-2 (narrow diamond)
I call it balanced formation as you cover all lines of field, if you see it clear, there are 5 lines in the formation field (def, def mid, Mid, Att Mid, Forward),
Right tactic should be: through the centre with red arrow on AMC, and 1 ST (especially who with one on one SA if you have in team), mixed pass, others remain default, optional blue arrow on DMC if opponents play with 3 STs
2. For 3-4-1-2 (the one I like and use, and tweak the most)
i call it Attacking formation, since you play with 3 defs only, the rest 7 are up-field, surely you must be playing attacking formation, so I normally teak it into 2 cases: (both cases use blue arrow on mid DC, Red on ML/R, AMC, 1 red optionally on 1 ST with highest finishing points, or one on one SA)
- Vs better team:
Attacking (or even hard attacking if you have nothing to loose), mixed focus, short passing (as this is mid based formation, and you are playing with 3 Defs, so carefully short passes at the middle of the pitch reduce chances of lossing balls and being victim for vulnerable counter attack), whole pitch with offside trap
- VS weaker or equal team:
hard attacking, mixed focus, mixed passing, whole pitch, offside trap
These were tested and confirmed to work great! Dont worry much about full pitch as it is defined as balanced def and attack, on the own half side, you def at your own half, but with whole pitch, you def at your opponent half, which will lead to less free kicks, corer kick given to your opponent and all dangerous situation happens far away from your GK. You can see my team in the signature!
Good luck and enjoy playing