Most float centers run a tight schedule with narrow margins for the transitions between floats. Oftentimes relying on their customers to take reasonably timed showers to fit that schedule. If a single customer takes a shower that's a bit too long, it can throw of the schedule for the rest of the day!
What if showers were in a separate room? Then customers could shower as long as they want! Ashkahn and Graham explain why this is an extremely bad idea.