Does it get better with practice?

Tried a flush with my wife over the weekend. Well,she tried one.
Olive Oil and lemon juice. It went down about as you'd expect and stayed down for a couple of hours. there was some aggravation with phone calls and some other general stress around the time, so I'm thinking this might have afected the outcome. About 3 hours after the last dose, whe barfed her insides out. She figured that all of the stuff came right back out again and that th ewhole thing had been a failure. About 36 hours later, she passed a few stones. She wasn't too keen on digging through it to see but she did find about 10 largeish (about 15 mm) stones, greenish brown with a sort of waxy makeup leading the way with a lot of light goo behind them which was presumably the little bit of oil following.
anyhow, the vomiting has put her off a bit, though she says she'll try it again when she has a bit less going on, but is not prepared to do it 10 or 20 times. She figures it'll kill her if she does! So the question is, does it get better? This process seems to be the only otion for her as an operation, aside from being a bad idea generally, is not really possible in her case as she suffers from adhesions with surgery. I'm hoping she'll press on with it.
also ,any advice on easing the whole thing? Half the amount, for instance? longer periods between doses? anyone have any views on any aspect at all?