Schumacher headed home Gregg Wylde's corner to clinch a point at the end of an entertaining encounter at Gigg Lane. The Shakers have picked up just two points in their last four games but Shirtliff insists they have been worthy of far greater reward.
He said: "It's becoming a bit of a habit that we're dominating teams and not finishing them off. But you've got to give credit to the players for sticking at it for 90 minutes and never giving in.
"It's frustrating we're not getting the results but I'm a big believer that if you keep plugging away and keep sticking at it, your luck will turn and the results will start going your way. We just have to keep our heads, keep chipping away and hopefully we'll get enough points to stay in the league."
Bury fell behind within the opening minute when Aaron Wildig scored but Shirtliff was delighted with Bury's response.
He said: "It was a disappointing start and it knocked us on the back foot but from then on we bossed the game. We were in control, played some good stuff and created some good opportunities. The players stuck at it and didn't drop their heads. With a bit of luck at the end it could've been a 3-2 win."
Bury hit back when David Worrall fed Matt Doherty and the full-back slotted a low shot under 'keeper Chris Weale. Shrewsbury edged back in front when Jon Taylor raced down the right to finish well, but Schumacher's goal left Shrews boss Graham Turner cursing his side's inability to close out games as they missed out on their first away win of the season.
He said: "I'm ever so frustrated because I see us passing the ball for fun at times, particularly in training, but in the last 20 minutes of games we keep inviting pressure by giving the ball away. We know they're chasing the game and they're going to leave men up front so you have to match them for that.
"There were so many times we could've got out with the ball and passed it with some precision, which we're good at, but we let ourselves down. I've never known a side who give the ball away so frequently when we just need to take the sting out of the game.
"We keep passing the ball to the opposition, which baffles me because we've got good passers in there. That's our strength. I've got to say, maybe we would've settled for a point before the game in the circumstances but we've got to start winning our away matches. Never was there a better chance than here."