Estimating repairs using BP Rental Calculator= shot in the dark?

[Jonah Selner]

I'm a BP Plus member, and love the Rental Property Calculator. But I'm struggling with estimating repairs when doing deal analysis.

In "The Book on Rental Property Investing" by @Brandon Turner, Brandon identifies and fills out estimates for 24 main categories of repairs (carpentry, electric, painting, siding, windows, etc.) on page 126. But he doesn't explain how he arrived at these relatively specific estimates (e.g. Garage= $500.) He just says you "might need to make some assumptions."

"Estimated repairs" is also a line item in the Rental Property Calculator.

My question is:

Isn't this "Estimated Repair Cost" a total shot in the dark? And if you get it wrong (and depending on how badly you get it wrong), wouldn't it completely change whether or not the property is a green light or red light for going to see in person/making an offer?

I understand it's an estimate and the point isn't to nail the numbers perfectly. And I'm sure it gets easier with time, as you get to know the area you're looking in. But are there any heuristics or tips for beginners like me who want to use the Rental Property Calculator to "qualify out" the 99% of deals that don't make sense to go see in person? I want to know how to even get in the ballpark of the same "assumptions" Brandon made on page 126 of his book.

As a newbie, I'm looking to gain action-taking momentum by analyzing 3 deals a day (as Brandon recommends), but I feel like there's no point when I could be tens of thousands of dollars off when it comes to estimated repairs.

Any advice? Thanks so much!