I don't think it's as simple as just conserving energy. Nothing conserves energy like substitutions, and other than that, getting a 4th and going 4-0 up in the second half would have killed off Brighton's resistance immediately and let the game play out at a walking pace - that's saving energy.
I think Pep's always been pretty consistent that when things get tough, he wants the players on the pitch to fix it. The reason Xabi Alonso described playing for Pep as an MBA in football is because he throws so much responsibility onto the players.
So another manager might see Brighton getting on top for 10 minutes and feel he needs to intervene, Pep sees it as the point where the players learn something by getting back on top. He wants them to find the solution themselves, whether that's by going back up through the gears after thinking they could relax, or by changing their play to counter Potter.
We have very few occasions when we're up against it, and that cost us at the beginning of Pep's time here because the players looked shocked and panicked when they went behind which lead to collapses or wasting 10 minutes trying to recuperate. These days he is more hands off, lets the players have more autonomy and as a result we looked much better last season when we ran into a setback in the CL like at Dortmund and PSG.