This is something a lot of people get confused reading Boon Focus 3 too fast. You don’t get a free action invocation of a boon, you only get the shortened length from Boon Focus 2 (in the case of Summons, a Major Action).
If the boon is somehow temporarily canceled, in the absence of other rules, you can invoke it again as a free action.
That first part has to happen before you can invoke it again as a free action, which isn’t something that happens very often, if ever.
With Boon Focus 3, however, you can just be walking around with your summons b/c you aren’t having to use the minor action to sustain them, and then when an encounter happens, you can summon an additional set.
It is possible this is what you meant originally, but the wording wasn’t entirely clear, so wanted to point it out just in case.