Preferred minimum pressure at furthest fixture | Terry Love Plumbing Advice & Remodel DIY & Professional Forum

Are there any rules of thumb about the preferred minimum pressure at the furthest fixture (in my case, a 3/4" bathroom)? Standard flush tank toilets. I believe the 2015 IPC calls for 20psi for thermostatic mixing valve showers, etc, but that cannot be a great experience.

What's the preferred minimum pressure?