What I recommend is setting up standard pattern that you use on each and every inspection when doing thermal imaging (for me, that is every home inspection). The inside IR scan of the house should include ALL areas of the house (plus… basement and attic). Outside IR scans have be planned with regard to the time of day, in order to work within the delta-t windows that mother nature gives you.
Your inside IR scans also have to be done in relationship to what adjustments and manipulations you have to make to enhance the delta-t environment. This is a lengthy discussion and cannot be covered in a short post on the forum. There are too many dynamics at play all at one time and the thermographer must know how to respond to these issues on the fly, as well as proper planning.
Various materials also require special considerations regarding the delta-t factor. The delta-t window is opened (if possible) in order to bring sub-surface temperatures to the surface in order for your camera to see them. What you are looking for and how you set things in motion to “see these defects” can affect the “time” it takes to do the IR scan. When issues are found, then the verification process can also add time to to the IR scan.
Then, each type of defect that you are looking for may require a set of actions that must put into play before you actually start looking for the subsurface evidence that is hidden without these steps.
It can take as little as 20 minutes to do an inside IR scan of a house, if there nothing strange along the way. Sometime you discover things that can be time consuming to verify exactly what you have found. As you can see… your mileage may vary.
A poor resolution camera, fuzzy mk, and poor optics can make the IR scan go faster because your 50% blind to the defects and do not realize why you got done so fast and found no defects. Speed kills.
Get some training and learn these step by step methods regarding the various types of IR scans of the structural and mechanical systems in a building… plus the verification process, report writing, liability issues and tricks of the trade to “get IR done”. (I stole that line from David Anderson).