The Iron Shirt exercises I practice do not involve pills or having to eat immediately afterward, nor am I restricted to a time limit or repetition without being able to do a shorter time or smaller number of reps. While I practice different exercises than the ones probably you are talking about, it seems to me like the people giving out the instruction are a bit cracked.

It's a general rule that you don't eat anything for a while after qigong or forms practice or whatever, and people generally recommend waiting an hour. Many advanced qigongs feature advanced breathing methods which can cause things like reflux if you eat before or immediately afterward, so it's advisable to wait. And I've never heard of having to take a pill, though it's probably an herbal pill, and there are some programs, usually in external arts in my experience, where herbs are used to supplement the training. However, I won't discount the practice within internal arts as well. But if the only place you can get the pill is through them, I would be wary. And the part about not being able to do a smaller number of reps is completely absurd, unless they mean that you must keep up the same intensity for the duration. However, while I have heard of Iron Palm programs where, once you start training, you cannot stop for more than a certain number of days without having to start over, they tell you that you have to start over and don't leave you hanging wondering the reason you can't stop training for over 3 days, for instance.

I'd ask the people for more in depth information, to clarify issues like these and if it's not forthcoming, I'd forget about it and move on to someone else's teachings.