The client insists every integration must be real time. How would you guide that decision?

I would ask what business decision depends on the data and how quickly it is needed. Many processes, like nightly financial reconciliation, work well in batch, which is simpler, cheaper and more resilient. Real time suits cases where users act immediately on the data, such as order status on a customer call.

I would present the trade-offs in cost, complexity, API limits and failure handling, and recommend the right pattern per data flow rather than one approach for all.

Look for business-driven reasoning and awareness of API limits and error handling. Strong candidates propose a pattern per integration. A pitfall is agreeing to real time everywhere without discussing cost and reliability.