Why your spreadsheet works until it doesn't
A spreadsheet is a genuinely good way to track two or three leases. The dates are visible, you built it yourself so you know exactly where everything lives, and it costs nothing. The trouble shows up as the portfolio grows and the spreadsheet doesn't change to match it.
The error rate is higher than it feels
Spreadsheets feel reliable because you can see the data directly, but that visibility doesn't prevent mistakes. Research cited by The Conversation found that 90% of spreadsheets with more than 150 rows contain at least one major error. A lease-tracking sheet across even a modest portfolio, with a row per lease and columns for rent, escalation, renewal windows, and notice deadlines, can cross that threshold faster than it looks.
A single wrong date compounds
The specific failure mode that matters most for lease tracking is a date entered wrong at the source. If a lease's commencement date or term length gets typed incorrectly once, every date calculated from it, the renewal window, the notice deadline, the escalation schedule, inherits that same error. Nothing about the spreadsheet itself flags this. It just looks like a normal row until the date it was protecting quietly passes.
What a spreadsheet structurally can't do
Beyond the error risk, a spreadsheet has no built-in way to know a date matters until someone remembers to look at it. There's no reminder that fires itself, no record of who checked a cell last or whether they acted on what they found, and no link back to the actual clause in the lease to confirm the number is even right in the first place. None of that is a flaw in the spreadsheet. It's simply not what a spreadsheet is built to do.
A small, simple portfolio can get away with a spreadsheet for a long time. The real skill is recognizing the point where tracking by hand quietly stops being reliable, which usually arrives well before it's obvious. RenewSavvy exists for that transition: structured dates extracted straight from the lease, reminders that fire on their own, and the source clause shown next to every value so you can check it rather than just trust it.