What to read a vendor case study for

Not the outcome. The outcome is always positive, which makes it uninformative.

Read it for the friction

What took longer than expected. Which step nearly derailed it. Who objected and why.

That is the part that transfers to your situation, and it is usually buried in a sentence rather than the headline.

The friction that shows up every time

Participation. Getting source photographs out of people who each have to be asked twice, in an organisation where some work shifts and some are remote.

The portrait production is never the bottleneck. The chasing is.

The second recurring one

The joiner. A session produces a matched set on one day and no mechanism for the day after, so the coherence has an expiry date measured in months.

What no case study will tell you

How the headshots looked on the two hardest faces in the company. Ask for that specifically, because it is the thing sample galleries are constructed to avoid showing.