Most line items in the model will not need summary calculations, so it is good practice to turn summaries off initially and add then back when necessary. This is especially true for Calculation modules and conditional formatting line items
Exception:
2.03-01a User facing modules on dashboards: For Input or Output modules, specifically those line items displayed on Dashboards, summary options are likely to be needed
Related to Rule:
2.01-10 Calculation Modules
Questions on this topic? See 2.03-01 Turn Summary options off by default in our Planual forum.