My hand wavy math.
One person dedicated to a single project / task baseline 100% total output.
One person split between two tasks / projects that require context switching, 70% total output at best, perhaps 50% total output, a loss of 50%.
One person working on a single task that they’re passionate about / intrinsically motivated to complete: 150-500% output.
When you have one task / project to think about and focus on, it engages your brain: sleeping, showering, walking, your subconscious is processing.
Adding just one extra project / task that requires a context switch mostly kills this subconscious processing mechanism.
But if that person has rare skills where at least 25% of their output makes another team of 5 100% more effective (200%), than than loss of 50% output is actually a 33% gain in output!
Say you have a team of 6 (5+1 DevOps Wizard), and a team of 5. so Call it 5x200 +5 x100% output, 1500 output total. Split our wizard in half and you get 5x200 + 5x200 = 2000 output total!
At a certain minimum level the effectiveness inverts because people are waiting on wizard magic and everyone is less effective, but there is benefit to having specialists be split.