In my  training I always make it a point to discuss planned weekend work especially for utility construction work. So you are working on an estimate where the estimator knows that a utility tie in (or whatever it is) can only be done on off hours on the weekend. Now I am not referring to regular work but this is something that a crew that is typically working during the week will have to show up to do on the weekend. The calendar for the activity should not be the regular work week calendar (that might have an overtime factor of 1.10) but an all overtime calendar since the crew will have already worked a full week. So what is needed is an all overtime calendar.  A couple ways to set this up. One is to put the number of hours for Sat/Sun when setting up the calendar and those hours will be all overtime. Another way is just to do an override overtime factor for the calendar. Both methods are shown below. So the true overtime cost is accounted for. This is especially important for a change order if the crew will be performing the work on the weekend.