Kata vs. Sparring: Which trains better for real fights?

So I've been looking up studies on old martial arts practices versus modern, live-training methods, and the results keep backfiring. A few academic articles I read argue that kata, as structured patterns, keep students’ footwork tight and ingrains muscle memory; other research claims that sparring's randomness creates a better mindset for real combat.

My question for this space: When you focus on self‑defence or competition, what’s the best balance of both approaches? Should the foundation be slow and methodical—repeating the same forms until you can perform them from instinct? Or should you drill in irregular contact environments to survive unexpected attacks?

A friend in the club suggested a 2‑to‑1 ratio: Kata 2, Sparring 1 for most students, because kata keeps technique crisp while sparring keeps it survivable. Others say any kata eventually feels artificial when an opponent is unpredictable. In the end, it’s hard to separate the psychological skill from the physical skill.

What does the experienced squad say? Are there examples, training programs, or personal experiences where one side clearly outshines the other? Looking forward to reading your solid takes.