Fortuna were ahead on five minutes via Danny Schmidt before Town sub Marcus Harness struck after halftime, but the Germans settled the game through Tim Rossmann.
“It was a useful workout,” McKenna said. “Of course, we didn’t play our best. I thought we had challenges with some of our pressing and off the ball stuff the whole game, but that can happen and it’s good for it to happen at this stage of the season.
“We didn’t prep the game at this stage of the season as we would in a league campaign, so there were some organisation challenges, but also some individual and unit things for us to improve on against a team who played very, very well and are further along in their prep from us and are getting ready for the league to start next week.
“It was a useful workout, a really good challenge. A shame about Wes’s ankle and we’re waiting to see on that but other than that lots of good minutes in the legs.
“The Premier League starts later than most of the other leagues, so that’s the nature of the fixtures, which is only a positive for sure because we still have a few weeks to go and we’re going to need the few weeks on all aspects.
“So playing a team who are a good side who were very close to getting promoted themselves last year and came ready for the league next week, that was a really good challenge for us and I think the boys felt that and it was a tough game, a good game.”