This is from Stephen Keenihan, managing director of Latent Petroleum (operator of Warro)

"We originally designed the well so we would frac a zone, produce it for a while, and then move onto the next zone. Unfortunately, when we took the standby costs of all the crews into the equation we knew it was going to be prohibitively expensive. We knew we would have an issue trying to determine what each of the zones was producing if they were co-mingled but it was a risk we had to take"

So it looks to me like Exxon is doing things the right way, even though it's a lot more expensive. Between each frac job the crews have to hang around, or pack up and head back to Scotland, Germany, or whereever they came from.