Note that in some areas of your stroke you will have great awareness but in others you will have gaps or holes where you can't really feel or judge what you are doing. It could be that in front of your head you are unaware of where your arm and hand is pointing, which can easily lead to a crossover:
Or during the catch you feel like you are pressing backwards but in fact are pressing downwards with a straight arm:
So gaps in your proprioception can easily lead to stroke flaws. It's why when you see yourself swimming on video and spot a fault you think "Wow, I could have sworn I wasn't doing that!".
It also explains why even when you become aware of stroke flaw it can still be hard to fix. It's not just a habit you have to break but a position in which you need to develop better proprioception.
Here's a super simple technique that you can try to identify flaws in your stroke and help you develop improved proprioception. It works best (but isn't limited to) when you have a stroke fault on one side but not the other, we call it 'Stroke Mirroring'.
As you swim, simply become aware of what each side of your body is doing and mentally compare the two sides. How does the left hand travel under the body and then how does the right hand do it in comparison? Are they different and if so which side are you going to tweak?
You can do this with any part of the stroke but make sure you try the following areas:
- The straightness of your legs - where do they point and do you ever bend the knee significantly?
- Where your hand and arms are as they enter the water and extend forwards (even when you breathe).
- How do your arms carry over the surface of the water?
- How are your shoulders and hips rotating to both sides?
- As you enter the water and extend forwards, are you keeping your elbow higher than your wrist and your wrist higher than the elbow?
Comparing the two sides of your body in this way can be surprisingly insightful. Make sure you are swimming normally with a good rhythm and spend around 50m on each area, moving on if you don't find anything interesting.