Hi there,
When you fly economy class between destinations in Europe on SWISS, you earn between 125 and 1250 Miles & More miles - depending on the destination. Business class flights between European airports earn 750 to 2000 miles.
A "Fly Smart" award return flight between European airports can be gotten for 20,000 miles. Fly Smart flights can only be booked online and must be booked at least 2 days in advance. So in the best case you can earn a complimentary flight after every 10 paid business class flights and in the worst case it will take you 160 paid economy flights to earn enough miles for an award flight.
It is worth noting that you can also earn miles by using Miles & More credit cards to pay for purchases. Depending on which credit card you use, you can earn between 0.3 and 1.2 miles per 1 Swiss franc of purchases charged.
You can compare airline credit cards by selecting "Frequent flyer miles" under "Reward programs" in the interactive credit card comparison on moneyland.ch.
Best regards from Moneyguru