The short answer
Manual abstraction, a person reading the lease and filling a template, produces good results at small scale and degrades with volume, amendments, and staff turnover. Abstraction software changes three things: speed on the routine fields, consistency across the portfolio, and durability, because the work product lives in a system instead of one person's head. The honest division of labor is software for extraction and date math, humans for judgment calls, and citations connecting the two so every value can be checked.
What manual abstracting does well
A careful reader with domain knowledge handles ambiguity better than any parser: the handwritten rider, the amendment that contradicts itself, the defined term used inconsistently. For a portfolio of five stable leases, a lawyer's abstract in a spreadsheet is a perfectly good tool.
Where it breaks
Volume: abstracting a portfolio by hand is measured in weeks, and reabstracting after every amendment rarely happens. Consistency: two readers abstract the same lease differently, which matters when you compare terms across a portfolio. Durability: when the person who built the spreadsheet leaves, the institutional memory of why cell C14 says what it says leaves with them.
What the software actually changes
Good abstraction software reads every document the same way every time, stores each value with its source citation, resolves amendment chains mechanically, and recomputes critical dates when the chain changes. It does not remove humans; it moves them to the right place, reviewing the fields that genuinely need judgment rather than transcribing the ones that do not.
The test worth applying to any tool: ask it where a number came from. If it cannot show you the page and the clause, you have replaced a careful reader with a confident one.
Bring one lease. Watch it get read.
A thirty minute walkthrough with your own document: the abstract, the citations, and the dates it finds.
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