king of avalon can be completed in 4 days. I prefer to spend a dollar on the special offer pack that gives a ton of speedups and resources. It helps by allowing you to level up faster to join a strong alliance. Once you join a strong alliance, you get more resources from joining rallies which makes the game way easier. Weak alliances won't be doing many rallies which means you need to farm resources and that takes way longer.

Rise of kingdoms is very easy but very grindy. It will take a week to finish it at the fastest but you need to put in hours each day farming things like barbarians.

AFK arena takes about a week but you need to really know what you are doing. If you make some mistakes, then you might not finish the offer in time.

Mafia city is very hard and not worth it for the sb. It would take more than ten days to finish and you have to know how to optimize everything.