Are there any benefits to short Z2 workouts?

Yep. I’ve not seen a head to head comparison on 1x4 vs 4x1. However if your goal is to train fat metabolism, here’s a post that says longer rides are better.

And the following is another link with same conclusion ie longer rides better.

https://www.peakendurancesport.com/endurance-training/base-endurance-training/fatmax-fat-fact-fat-fiction/