If your plan is created monthly, and however your view options are set to weekly, you may see additional values for a week where there are no ETCs.
This happens when your fiscal periods monthly and weeks do not follow calendar periods.
Note that you need to have weekly fiscal periods created. Monthly fiscal periods cover 5 weeks so each group of 5 weekly fiscal periods fits into a month.
STR:
Fiscal Period set-up
In MUX Assignments set the View to Weekly
Add ETC for all but the last week in the period.
8 ETC
Notice that Week of Nov 17 has no ETC
Plan is monthly and populate from Assignments. Then make the cost plan details Per-period metrics set to weekly. The values show in the last period as well where there is no ETC.
Notice that the Grand Totals for Units = 8 but if you add up the units it equals 10
This has to do with changing the per-period metrics to a view that is different than the cost plan period type.