Earlier I used to get different number of keys ranging from 1 to 10 but in last two events the number..

But it used to be fun to receive different number of keys ranging from 10-1

Agree, pretty boring if it's always the same. Might as well give us 1 key and drop the goal to a third.

The last 2 challenges was getting average of 5-7 keys par scenes, this one I get 1 at the time and between 2 and 10 when doing the jobs :( The chance of success to finish the challenge are impossible when I have 700 keys to find in 48hrs and health bar only 100 points taking about 2hrs to refill. If I do my maths right, between scenes and jobs I be need about 120hrs to achieve this !?.

Some buy the extended energy bar for 799 diamonds. It allows accumulation of energy to 150, and all character puzzles and starboosters will give 150 energy, too. When you buy, one-time only, you get 450 energy. Also each completed landmark gives 15 energy every 10 hours, so more advanced players get more energy. Players that are in active clubs and share coffee regularly have incredible amounts of additional energy. With all the opportunities for energy, game devs have increased the # of keys to reach the goal to keep it challenging.