Comment 25 for bug 1335323

Every time you operate, the first thing ASDF 3 does is to upgrade ASDF itself. It not done first but somehow required, the upgrade would completely break the build in midcourse — as happened to me more than once with ASDF 2. The previous solution was to take complicated measures in your build scripts to always attempt to upgrade ASDF first; I found it easier to fix the issue than to document the workaround. The asdf cache makes that cheap: only the first call in a given cache session will entail filesystem search and and possible upgrade of ASDF.

So, if you call operate many times in your cache session, (find-system "asdf") will be called as many times. If some of your systems explicitly depend on asdf, (find-system "asdf") will also be called accordingly.