Plumbing has begun

The Plumber started roughing in the drains for the bathroom. That's good, as far as it goes, but for the second time in three days we discover that my fancy high-tech construction plans are more precise than accurate. Or, more to the point, a detailed plan isn't necessarily a good plan.
In this case, the plumber pointed out that the plan didn't leave very much room between the shower on one side and the toilet and vanity on the other. There is space to move the wall 8-12 inches farther out so there would be plenty of space in the bathroom. But he wanted me to review the measurements before he does that, which I can't do until I get home from work tonight, so he quite for the day and will finish up tomorrow. That is fine; I am not scheduled to start filling the trench and cementing it over until Saturday.