Screech - clunk.....
Disclaimer - the following information is based on my opinion, my experience with snakes and what I have gathered from others over the years. Feel free to agree or disagree. All I ask is to keep it civil.
One problem I see over and over again with keepers, both novice and even some of the so called experts is overfeeding. Snakes by design are opportunistic feeders with the capability to go loooooooong periods between meals and gorge themselves when food is available. Being ectotherms, they do not need anywhere near the same caloric intake as a mammal. Since they get their warmth from outside their bodies, they do burn calories to produce heat inside. Most of the calories they consume go into growth. Slow growth is muscle tissue, fast growth is fat cells.
Problems occur in captivity when the food opportunity keeps presenting itself while the long fast period never comes. This can lead to overweight, fat snakes. Some breeders will even intentionally overfeed (called power-feeding) to try and get females large enough to breed quickly. I've seen lots of pics (way too many IMO) of boas with tiny little heads and huge fat bodies. Even rolls around the vent from all the stored fat. The unfortunate reality is this leads to fat unproductive snakes. Sure it may breed a year or two earlier and because of that you might be the "first" to produce some new combo morph. But at what cost? That original animal is likely to never be a good breeder. May never produce a decent litter and likely will die at an early age. IMO fat snakes say a lot about what an individual is in the hobby for - fame and/or the almighty $$$!!!
I start my baby boas on rat pinks or hopper mice. Once eating they go on a weekly feeding regimen. If I'm low on feeders on a given week, so be it, famine time. Going a week or two or three will not harm them, just keep them lean and hungry. Through their lives I keep the prey size on the small side, if you can see the lump because you know where to look, that's OK, if you can see the lump because it's all stretched out, probably too large.
By the time they are 6 - 8 months old, I switch over to a two week schedule.
For my adults, it depends on what is going on, females recovering from producing a litter may get fed every two weeks while other females and most males are monthly. My goal is to keep my snakes lean and healthy, not fat. I've seen my females bounce back to a normal lean looking snake within weeks of delivering babies.
I know some people go with 10 and 20 day feeding cycles, I stick with weekly so each group has a feeding day.
Monday - feed all the babies
Tuesday - feed the sub adults due to be fed that week
Wednesday - feed all the adults due to be fed that week.
Wednesday is also my rodent colony cleaning day. The feeding days are designed to consume feeders from the colony right before cleaning to allow easier cleaning and give me empty tubs to cycle the rest of the feeder colony into.
A typical healthy growing up boa will have a squared off shape to it, taller than wider. Of course they are all individuals, not all are squared off. Just like us, lean does not necessarily mean chiseled 6-pack abs, but fat can never mean them.
Please feel free to comment, disagree, agree - whatever floats your boat. Right or wrong, these are my opinions on feeding..
-----
Thanks,
Dave Colling
www.rainbows-r-us-reptiles.com
0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)
LOL, to many snakes to list, last count (05/26/2009):
36.51 BRB
29.42 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 
