>you break the transformation across many cells

In theory, yes. But the reality, nobody does that unless an error is apparent and needs to be investigated. The vast majority of calculations in Excel spreadsheets are done using cumbersome, multi-line, unreadable formulas that try to pack as much logic as possible into one expression. Such obscure formulas are the main reason why lots of business-critical Excel spreadsheets contain grave errors, many of which are are never discovered.