I forgot to say- as my baby gets older, I've noticed that my body more quickly responds to his changing needs.
What I mean is this- I work full time monday through friday (teaching) so on those days he nurses at 7, then 12, then at 5 when I get home. On the weekend he nurses constantly. So at work, my breasts stay pretty empty until about 11, and by 12 they are nearly engorged. Then they stay empty feeling until about 4 and by 5 there's a ton of milk for el. On the weekend, they fill steadily since he nurses every 2 hrs. If I happen to take a sick day, el of course wants to nurse steadily throughout the day, so he nurses at 7 like normal, then at 9. At 9 he gets barely anything (since it's a work day) but the rest of the day there's plenty, like my body says "oh it's not a weekday after all!" and ups production.
When he was smaller, my body was a little slower on the uptake. I'd have very little milk throughout the day on saturdays, plenty on sunday, and then monday I'd be engorged and leaking at work, but by thursday it'd be under control again- only to greet the weekend nursing frenzy again and start the cycle over again.
My let-down sensation is weaker now, although I know he's getting lots of milk. I don't leak between feedings. In fact, we are into such a routine that I don't even leak from the other side while he nurses the first side, even at school where there's a ton of milk letting down. It does change over time. As long as baby is healthy, I wouldn't worry!