Sales teams in three regions must only see their own region's accounts, but a global key account team needs read access to all strategic accounts regardless of region. How would you design the sharing model?

I would set the Account OWD to Private so the baseline is least privilege. A role hierarchy by region gives managers visibility into their reps' accounts. For the key account team, I would flag strategic accounts with a field and create a criteria-based sharing rule that shares accounts meeting that criterion with a public group or role containing the key account team, as Read Only.

I would test with representative users in a sandbox and document the model, because sharing becomes hard to reason about as rules accumulate.

Look for starting from least privilege and opening access deliberately, using the right mechanism for each need. Candidates should know criteria-based sharing rules and public groups. Pitfalls include making the OWD public and trying to restrict afterwards, or overusing manual shares.