Keys or lock box?

[Michael Donatucci]

I am hiring sub contractors to work on a job I have with a family friend as a GC mentor. Neither of us will be guaranteed to be there every day, but will be most days. What is the best mode of operation to make sure subcontractors have access to the house? Does it make sense to give out multiple keys, and then change locks at end of project? Or is it better to have a lock box and keep a key in there? Any thoughts appreciated!