I don't think they can put on weight too fast. They are opportunistic eaters so they will eat when food is available provided there are no other variables that might prevent it, i.e. shedding, already full, etc. It really depends on your plans for him. If you are trying to grow him up to size to breed quickly, you could have him on an every 5 day schedule until he reaches about 600 to 700 grams. Then go back to once a week. If he is just a pet and you don't care how fast he is growing then once a week is fine. Are you planning to pair him with a female and is she already approaching breeding size?