Differences between supervisors

On my recent cardio placement, I was at a cardiothoracic ward. On the ward there were 2 physiotherapists who are sharing the clinical duties due to the staff shortage. On the ward, we were mainly following one physiotherapist in the morning, and in late afternoon (after 3) we have another physiotherapist to supervise us.

The differences between the supervisors were not as obvious as the start. I was new to the ward, protocols and rules were to be learned and followed. Soon I became more familiar with the ward and patients. I started to think out of the box and noticed the difference between supervisors. All of heart and lung surgery patients have a lot of attachment when they are seen Day 1. SCC and ICC in particular needs to be careful placed before moving patients especially when ambulating. One supervisor on ward hangs the draining bottle on the lowest railing around their shin height while the other one places in the cage just above the cage which would be around the knee height. When I am with different supervisors, I have to adapt to their particular way of positioning of the bottle. I understand the rationale of both positioning, however I didn’t think such a slight difference would matter. Each time I positioned the bottle differing to their preferred method, I was corrected. And with one supervisor it was counted as a “safety” error as well, which seemed very unfair to me. There wasn’t a particular protocol in regarding to positioning of the draining bottle. From what we learned as uni, as long as the bottle was lower than chest it would be draining. Other similar experiences also occurred in regards to if ACBT should be given to patients who are able to clear sputum by themselves effectively and their sputum are of same consistency, colour and amount pre-admission.
I found as a student, such differences are so subtle, however when supervisor makes a big deal out of it, the whole situation becomes a very stressful experience. It feels like to me that the supervisor is just looking over your shoulder to pick out the little ambiguous errors which may be perfectly correct to other physiotherapists. I found it to be an obstacle to the learning experience. It seemed that I have spent time unnecessarily correcting different ways to do a task rather than spending time having more learning experience on Xray or handing over etc.
Has anyone else had similar experience and how could I handled it differently rather than adapting to different methods?