Different experience levels of estimators and whether a company is self-performing a work or subcontracting it out result in differences in the levels of details in which estimators would like to interact with historical production data. Different interaction patterns of estimators need to be understood when designing information systems that leverage historical production rates. This paper overviews an approach and a corresponding prototype system, which can store production data and contextual information items in a way that supports interaction with them in multiple levels of details (Kiziltas and Akinci 2008). The prototype system was used to conduct think-aloud walkthrough usability tests, within which users performed a specified task while talking about what they are doing during each step. This paper provides the results of these think-aloud walkthrough usability tests conducted with general contractors from heavy/civil and building construction industry. Analysis of the test results showed that estimators interact with historical production and contextual data at different levels of details depending on their experience levels and whether most of the work done by the company is subcontracted out or self-performed. It was observed that senior and lead estimators, who work in companies that self-perform, look into historical information in more detailed levels as compared to estimators, who work in general contracting companies that subcontract their work.