From my knowledge, laning phase generally ends when the first tower falls. The reason for this is because it is more often better / safer for the "winners" of that lane to apply their pressure to other lanes, leading to more outer towers, and generating more control of lanes around objectives.
I say it is "safer" because trying to press waves into the inner towers without strong jungle control (keep in mind, this is the enemy's jungle) will make it easy for the enemy jungler to catch you out of position.
By swapping with top or mid, the laners that are already ahead are able to continue to snowball their lead as well as forcing the team that is behind to react to their pressure. This can create a vacuum effect, drawing stronger / more enemies away from allies that are behind, allowing them to catch up and apply free pressure on other objectives.
For example, you win your bottom lane first tower then swap with top, your top laner is then able to hold minion waves off of a tower with little pressure because the enemy team would need to play around a contestable portion of their jungle, without the protection of an outer tower. Meanwhile the jungler / mid laner can assist with contesting that portion of the jungle or assist in applying pressure top or mid. Now the enemy team needs to decide if they want to try to match pressure across the map against a team that has a lead, or focus their strength on one side of the map or the other. So in this example, they need to either send more players to the bottom side of the map to match pressure by taking objectives, tower or dragon, .. which will most likely cause them to lose objectives top, tower, Rift Herald, or Baron. OR, do they send players top to defend the objectives top side, giving up control over that portion of their own jungle and giving away a free dragon.
Before all of this though, ... I'm going to give you another YouTuber, SoloRenektonOnly. This guy is honestly my preferred 'lane management' YouTuber. He often talks about when is a good time push, when to back, when to roam, and why. He is a top laner, so there are some tiny differences, but the overall concepts apply.