I wanted to reduce the lease time on a DHCP scope
$lt = New-TimeSpan -Hours 12
Set-DhcpServerv4Scope -ScopeId 10.10.54.0 -LeaseDuration $lt
You could even make it a one liner if you wished
Set-DhcpServerv4Scope -ScopeId 10.10.54.0 –LeaseDuration (New-TimeSpan -Hours 12)