Your exercise programme, you always starts with Squats. They are the hardest exercise and the backbone of the programme. If you Squat second or least you will make them harder because you are already tired. So you are more likely to skip them. Squat first so you can not rationalize your way out.
Secondly, you do Bench or Overhead press. This gives your leg and lowers backrest before you need them again on Barbell rows and Deadlift. If you reverse the exercise order you will struggle with those exercises. Your lower back and legs will be tired from Squat. You need them for Rows and Deadlift.
Starting with Deadlift tires your lower back for Squats. Squats tire it for Deadlifts too. But you only Deadlift for 1×5 after Squats. Squatting for 5×5 is heard, and Squatting for 5×5 after Deadlifts is even harder. You are going to be tempted to cut your Squats short or skip them altogether.
Sticking to the same exercise order every workout also makes it easier to track improvement. If you keep everything constant except the weight, then you know that when you can lift heavier it’s because you got stronger. Not because you did this exercise first today and were fresher.
Don’t Squat one set, Bench one set, Row one set and then go back to Squats. Do five sets of five on one exercise before moving to the next one. Stay focus on one exercise instead of reaching from one to the other. You will have a better technique which will healp you lift heavier weights.
The power rack may not be free when you arrive the gym. Or the Bench might be taken when you are done Squatting. You encounter these situations all the time but never change the exercise order of your workout.