Sale Sharks director of rugby Steve Diamond says European competition adds extra "stress" to an already intensive Premiership season.
Diamond's side finished bottom of their Champions Cup pool last term, losing five of their six games.
After an inconsistent season, Sale finished 10th in the Premiership, 20 points above the relegation place.
"Our form was good. We lost to Toulon and Saracens and beat Scarlets but it takes its toll," Diamond said.
Speaking to BBC Radio Manchester, he continued: "The problem is that in the domestic league, that's where your bread and butter is. In a competition that has relegation, one thing you can't afford to do as a franchise is get relegated.
"So all your intentions are good in all competitions but you've really got to put the hard graft in and make sure you stay in the league and we did that comfortably."
Despite Sale not finishing in the top four of the Premiership since their title-winning 2005-06 season, Diamond believes he can bring success to the north west.
"A lot of people's ambition is to finish in Europe. Mine isn't to do that, it's to manage to be in the top four [of the Premiership]," he added.
"With the investment that's gone in this year, we've got to see ourselves being a regular top-four side in the next three or four years.
"There's no doubt we can do that. We run a business that doesn't lose any money. The sides that traditionally finish below us lose around £8-9m. We don't lose anything."