In an IT patent dispute the decisive question usually reads like this: are the features of the independent claim implemented in this particular product. Answering it takes not a general impression but a mapping of each feature onto technical materials.
The sources can be user documentation, network exchanges, APIs, test results, public materials, source code, an expert inspection, and indirect indications of how the system behaves.
The earlier a technical map of the features is built in a matter, the easier it becomes to separate strong evidence from assumptions.