January recruit Julian Draxler scored twice as holders PSG routed Rennes 4-0 away from home on Wednesday.
PSG were without Marco Verratti, Angel Di Maria and Thomas Meunier for the trip to Roazhon Park, while captain Thiago Silva and leading forward Edinson Cavani were rested on the bench.
However, Hatem Ben Arfa stepped up with a goal and Presnel Kimpembe and Christopher Nkunku impressed.
"We're learning our lessons from the first half of the season. At certain moments, we had injuries to deal with and that influenced the team's performances," Emery told Eurosport 2.
"We spoke about increasing the competition for certain positions. Verratti, Di Maria and Meunier were injured, and players like Thiago Silva and Cavani didn't play. We will be playing every three days.
"We need all our players. With that many matches to play, there is the possibility of injury and fatigue. The team changes but we are still turning in good performances.
"It's important in order to maintain our high standards. Ben Arfa scored, Areola kept a clean sheet, Pastore made an excellent return to action, as did Kimpembe and Nkunku… they're ready."
Draxler was particularly impressed as he continued his fine start to his career in the French capital.
"We didn't play our best football in the first half, but our first goal made things easier for us. At 3-0 we had a lot of space, and that's what we like. That made the match easier for us, but it wasn't easy in the beginning," Draxler said.
"It's my first season here, and I want to win titles. The Coupe de France is one of them."