okay so some disclaimers up front. I am NOT an expert, just opinionated.
Who: someone who has technique down, already has a decent level of strength, and is pretty busy with work, life, school. etc. as most complexes take 30min tops to complete.
When. your low on time, you've come off a serous limit strength cycle and your conditioning has taken a back seat. as part of/ complete hypertrophy protocol.
@kennycro@@aol.com is correct, other more effective ways exist. but it is a great compromise between a variety of goals when on a time budget. (endurance, some strength, hypertrophy.)
How: build it around squat, hinge and pressing movements. use a weight that you can feels good for 6-12reps on your weakest movement. you can play with some combination of density, volume and load as the weeks progress. or better yet get someone with experience to tell you how to. may I suggest
@Hector G Double Kettlebell Manifesto, 701 a.
I've been thinking about complexes in the context of HIRT training like in this article, but im not an expert so likely ill let someone else say if its a good idea or not.
HIRT for Hypertrophy
bears repeating all of the above is IMO.