imo better do *5 x 1 for each color which is for aw/raid defense purpose
then do *4 x 5 for each color and totally you will have 30 maxed hero , its mandatory for AW Offense
after that you can do single feeding to any *5 you had , no need to do colour feeding anymore for fast leveling.
for Feeder , if you are C2P , spare 3000 Gem to reset WE every month for Atlantis Rise and do Auto-Farm at S2-1-2-N , you will get around 1000 backpacks , use 3 of your TC to train each 333 ( a Week ) , with 1000 backpack and any feeder you get in week you should able to max 2 *5. i just done with my Tarlak last week and do-ing Seshat right now (4-44) , food is bottleneck
for *3 , after *5 reach 4-50 , i gave *2 feeder to *5 and *1 feeder to *3 , 4-50 are too expensive for *1 feeder , that could be your point to save food and feed *3 in same time