As short-lived as I want them. Recreating them is one command and about 10 seconds (I have scripted apt/gem/etc installs as a part of the recreation). I tend t

As short-lived as I want them. Recreating them is one command and about 10 seconds (I have scripted apt/gem/etc installs as a part of the recreation). I tend to use them for a bit, and then destroy/rebuild. Think days, not weeks.