Perhaps I misunderstood the problem you were talking about. I thought it was leaving a key unprotected. A lockbox resolves that, by restricting access to the key to people who know the lockbox combination.
You mentioned rekeying the lock after the work, so I assumed that key copying wasn't the issue as you found a solution for that.
Rekeying the lock is the main issue. It costs money and then you need to redistribute keys to anyone who has one (other family members, nanny, cleaner, etc.)
