[AlotOfReading]

Some do assembly, some don't. Depends on the house and each one will have slightly different constraints on what they'll assemble. As for costs, it balances out with the costs of slower iteration. When EEs don't have fast turnaround (or too short schedules) they start loading all their little experiments onto the iterations they do have and you can end up with bloated BOMs, overspecified parts, and "good enough".