From QB user:

Combining all triggered builds into one build is something I have considered. One of the challenges with this approach is that one of the three triggered builds uses extensive parallel steps and runs 27 steps at the same time across different agents. This creates some visual challenges with the current UI, especially if 2 other builds were running in the same UI at the same time. But if the UI had a way to visually collapse steps while in step-status mode I would probably consider moving them all to one configuration.

Is this something that your team has considered? I.e., if I had 3 composite steps that ran in parallel:

Build on Windows <--> Build on Linux <--> Build on Android

Each of those composite steps would have many child steps that actually do the building. But a user of the UI might want to collapse all of the activity for Linux/Android and only focus on the Windows step. I don't know how challenging this would be with the current UI framework, but several of our users have mentioned variations of this idea. The parallel jobs create such a wide UI experience that adding two other builds to the already-busy page might be a negative experience for our users.