Dhama, your interest for motivating the people on that theme is well coming and your concern in the participation and very fair. 
Leaning that challenges are for beginners, where they can test your learning with the opinions of the more experts. 
Perhaps it is for that that the participation in most of the challenges is scarce. 
The great artists don't participate, perhaps because the challenge doesn't give real prizes. 
To participate of challenges for the recognition doesn't have sense very, since in the our works receive praises, comments and critics day by day; and that is enough for our learning. 
How do our works in some way go by a proof, then which the sense of participating in a challenge? Fame?, prizes?. 

I announced of almost all, and in all I placed works of tests. 
It would be very interesting and useful that the votes were accompanied of observations on the work to improve our learning.