You can also do 3 Table Service meals too (if they are all one credit).
The type of meals do not matter (Counter service or table service). It is the number of credits that count. Any combination of 3 credits per day will work.
E.g.
3 TS meals (1 Credit each)
1 CS, 1 signature table service meal (2 Credits)
1 TS meal (1 credit) and 1 signature table service meal (2 credits)
2 CS, 1 TS meal (1 Credit)
1 CS, 2 TS meals (1 Credit each)
etc.
And you can mix it up. Do all counter service one day, do a table service and signature the next day, etc.
Now, whether some combinationa are WORTH it or not, is a different question. Would 3 CS per day be worth it? I haven't done any calculations, but I would say probably not.
Maggie