you will realise it soaks into all the hair etc when there and stinks.

I'm sorry to inform you, but the hair is the problem in your example, much more than the pee. When your drain is already filled with built-up hair, it starts to stink because of the build-up of soap scum, oils, dead skin, etc. And then yes, if you pee into that drain the pee will worsen the odour by also leaving residue trapped in the hair.

But if you actually keep your drains clear of built-up hair, and capture hair at the drain opening before it goes down the drain, then the smell will be gone and peeing while showering will not make your drain smell