The problem is that they develop eggs, mated or not, when conditions are right. If conditions are sub-optimal, they will delay develepment of eggs usually. It's very hard to get them laying small clutches after huge clutches. They tend to follow a trend for a while, especially if you have no means of really cooling them down - low 70's or 60's at night.
I've been keeping veileds for about 15 years, and I've tried all sorts of things. What works best for me is low feedings (it's healthier for them, and cheaper for me), and cool night time temps. I usually had clutches in the 30's and 40's in Raleigh. After moving to the mountains, where temps are never higher than the 70's at night (and almost always cooler), I've not had a clutch over 35 - all but one were under 30. And I've increased feedings compared to when I lived in the warmer lowlands.
I never limit their light, and I never let them go for long periods without food. Those things may be effective in keeping non-breeding females from developing infertile eggs, which will probably increase their life expectancy. I'm not looking for unnaturally long life, but a very long, natural life - I breed all my females, and I want them to live as long as possible while still breeding them.
If you have a single pet, you want to listen to kinyonga - She's got the "long lived, non-breeding, female veiled" thing down pat.