Sorry only seeing the question about why I shower the cats now. I wrote a reply this morning and lost it
Cats are showered in the evening after they have been fleaed / wormed, the stuff has been given time to work and it gets rid of any remains.
It also keeps them acquainted with the shower so they don't totally freak when some of them need it more often. Cats around here often end up very oily (I'm not talking about headbutting underneath cars type).
The area I live in it has a lot of illegal fuel laundering in the general area but not aware of exactly where and the remains of it are also bad for cats and the cats seem to get in oil a lot, not good for them to try and clean themselves off with kerosene so when they aren't totally scared of the shower it helps as it's not their only experience. It seems to be they roll in it and then go straight home where they or mine is boxed and got ready for a shower.
I try with the oily cat to only do the exact bits needed and no more but sometimes it needs to be all.
For example in the past week alone, there have been 3 arrests in the area for fuel laundering and its effects in recent weeks and I have seen on local news website there are more awaiting court dates.
The other option is to keep cats inside all the time but as soon as a door or window is opened, they are heading out and the last resort is to shave them to get oily fur off, thankfully I have never had to do that.
Its an ongoing problem in this area, all can do is protect them and sort them out. None of them has got sick in recent years despite some very oil covered cats, so it's doing the best for them in the only way possible. They can't be kept in voluntarily despite how many toys or attention etc and we all as owners hate them wailing all the time to get out and very distressed.
Police have been working on the fuel laundering over the years but it seems to be more prevalent as Brexit nears as where I live borders with the Republic of Ireland closely