In my line of work I often see tech vendors and consultants trying to plan infrastructure changes using Excel (or worse, tables in Word, but we won't go into that). The results are horrendous.

They start with a manual inventory of the configuration in question, type it ad-hoc into a spreadsheet, then go through making manual changes, notes and additions until it feels good. There's lots of highlighting, different coloured text, etc like layers of sedimentation. Formulas are only used for sums and counts in an ad-hoc way.

The end plan always contains mistakes and omissions that really hurt during deployment time.

The correct way requires discipline: immutable input sheets (from machine-generated config dumps), a parameter sheet, output tables (with consistent usage of formulas with "$" notation to lock rows and columns), and cross checks with conditional highlighting.

Unfortunately this is really hard for people without programming instincts/experience. Good job security I guess. But if you can do it, it's both faster and safer than the manual free-form method.