One goal up and playing with confidence levels sky high, City looked to be in with a decent shout of making it four home wins out of four just under half an hour into their contest with Colchester United two weeks ago.
Two quick-fire goals in the space of four minutes from the visitors - the first goals Parkinson's men had conceded at home all season - put City out of their rhythm and left them with work to do in the second period.
The Bantams did, of course, recover to get a richly-deserved point out of the match, but Parkinson reckons the jolt his side received in the Colchester fixture will hold them in good stead going into future matches at Valley Parade.
Parkinson said: "In any game you take lessons with you which you can learn from to help you throughout the rest of the season.
"I thought against Colchester we started as well as we have started any game this season.
"We got the goal and I just thought we rested on our laurels slightly.
"We will be reminding the lads as we go into this game (vs Shrewsbury) that you need to have a ruthless approach from the first minute to the last to get those valuable three points.
"Obviously, we asked for a response from the lads after being 2-1 down at half time in that game (vs Colchester) and they gave us one in terrific fashion. So much so, we probably should have gone on and won the game.
"It was just that small period before the break where I felt we just took our front off the gas slightly.
"It is a good indication of how far we have come and much we have raised the bar, however, when we are disappointed to only pick up a point against a good side like Colchester."
The draw with Colchester extended City's unbeaten start at home to four matches. Parkinson knows that with every impressive result the Bantams manage to achieve on home soil, the greater the likelihood of teams coming to Valley Parade looking to frustrate and stifle his side.
While this might by the case in future games at BD8, having seen opponents Shrewsbury in action, Parkinson doesn't believe this Saturday's visitors will be after anything other than the win when they make the journey north this weekend.
Parkinson added: "When I went to see Shrewsbury play Bristol City, they went to win the game.
"They were quite a positive team.
"You could tell by watching them that they work hard on the structure and shape of their team.
"We will need some patience on Saturday - teams are going to come to Valley Parade and try to make it difficult for us - but they (Shrewsbury) are a positive side.
"Similarly to when we played them in League 2 a couple of seasons ago, Shrewsbury are a team that really reflect their manager.
"They play good football and a lot of their players look comfortable on the ball. Graham (Turner) seems to have improved their team from last year as well.
"As much as we look at the opposition, which we do as it is vitally important to do so, most of our training during the week is geared around how we are going to play.
"Hopefully our key players can cause Shrewsbury's defence some problems. If we are at our best, we have players who are very difficult to cope with."
Carl McHugh returned to training this Thursday after a recent groin problem to give Parkinson another option to choose from ahead of this Saturday's Shrewsbury encounter.
McHugh's return means that, apart from Matt Taylor, who is currently away on loan at Colchester, Parkinson should have a fully-fit squad to pick from for the visit of Graham Turner's team.
Parkinson said: "Carl has had a few knocks in terms of injuries since pre-season but he is back in training today (Thursday).
"He has a massive part to play with this club, and it is good to get him back out on the training ground because the effort and enthusiasm he puts into training really spreads throughout the squad."