Android had a quick deploy feature where you could push minor changes like text or layout updates to the phone while testing without having to actually rebuild it. Like press button and a couple seconds later it updates.

It without fail over years and years of trying to use it, always failed frequently, and you'd end up with unexpected behavior or crashes. For a time anyway, they tried to default it to on.

Im not sure what the current state of it is today, I just stopped bothering to test it out.