Unlike most programs, spreadsheet values update with every press of 'Enter'.
High resolution monitors and the fixed pixel height fonts that are common for many programs are a recipe for stressing eyes. Unlike such programs, spreadsheets are zoomable and pannable.
Unlike many programs, spreadsheets allow for multiple views.
Unlike the Swiss army knife that modeling programs are, spreadsheets are configured and optimized solely for calculations.
Piping systems must be 'connected' to use calculations native to modeling programs, and connecting systems is tedious (and budget sapping).
Your staff primarily responsible for modeling may not be the staff primarily responsible for calculations.
DoveTailTools spreadsheets include numerous features for minimizing data entry, such as customizable profiles for automated sizing of pipes.
DoveTailTools gas and water service spreadsheets don't just perform calculations for the pipe sizes that you have selected, they also include profiles that allow for 'one-click' resizing of entire piping systems.
DoveTailTools piping system spreadsheets are configured for input of complete piping systems. (Though, with judicious use by experienced personnel, they can also be used for critical path analyses.)
DoveTailTools spreadsheets include comprehensive user manuals.
DoveTailTools piping spreadsheets segment drop down lists are dynamic, such that segments that must be referenced once and only once can only be referenced once. Segments, once referenced, no longer appear in the drop down lists, and when segment references are deleted those segments reappear in the drop down lists, such that reference errors are essentially limited to renaming of segments and not to unconnected segments and duplicate segment references.
The almost inevitable modifications to piping systems as a design progresses often include renaming piping segments, and such renaming necessarily results in reference errors. DoveTailTools spreadsheets include font color feedback that bring such errors to your immediate attention.