The usual answers are five minutes, ten minutes, or "as long as feels right", and none of them explains what is actually different about a longer session.
Something useful can be said about that, because most breathing patterns have a property that makes the question simpler than it looks: they do not build.
A resonance session is five seconds in and five seconds out, and it is exactly that at minute one and at minute twenty. Nothing accumulates, nothing gets harder, and the last cycle asks the same of you as the first.
That is true of box breathing, 4-7-8 and extended exhale too. It means the length of a session is not a difficulty setting — it is just how long you are doing the thing.
Wim Hof is the exception on this site, and it is a real one: the rounds get longer as they go, so a three-round session is genuinely not a longer version of a one-round session. That is why it is set in rounds rather than minutes.
Two things. The first is attention: the first minute is mostly spent arriving, finding the pace and stopping fiddling with it. Everything after that is the session proper, which is a reason not to set two minutes if you can set five.
The second is the pace itself. Holding an even five seconds is easy for a minute and takes more care over ten, and that is the honest way to find whether the pace you picked is the right one. A pace that falls apart at minute six was a pace you were holding rather than following.
The timer here runs from one minute upwards, and the default is five. Five is a reasonable starting point for a pattern with no holds, and it is long enough for the arriving-minute not to be most of it.
For box breathing and 4-7-8 the control is rounds rather than minutes, because those patterns are counted in cycles and a round is the unit people actually think in.
Whichever it is, set it before you press Begin rather than during — deciding how long to keep going, while going, is a second task.
Ending a session part-way through is an ordinary way to use one, and the app records what you actually did rather than what you set.
There is nothing to break. No streak is kept here, no goal is set, and a session that ended at ninety seconds of a five-minute setting is a ninety-second session, not a failure of a five-minute one.
The timer below is the app, running in this page. Set the minutes before you press Begin — it opens at five.
The pattern In 5 s · Out 5 s
Five minutes is a reasonable first setting for a pattern with no holds, mostly because the first minute goes on arriving. For counted patterns like box or 4-7-8, four rounds is the equivalent starting point.
A longer session is more of the same thing — these patterns do not build or intensify. What changes is how much of the session is spent actually following the pace rather than settling into it.
Nothing here requires a minimum. As a practical matter, a session under about half a minute is mostly the act of starting one, which is why sessions that short are not recorded.
That is information about the pace rather than about you. Try a second longer each way; a pace you can follow without effort is the one to use.
No. The app records what you did, not what you set, and keeps no streak that stopping could break.
On your phone it runs with sound and haptics, and it works with no connection at all.