Is it ok to use ceramic spray without the prep steps?

I was looking into ceramic spray as an easy alternative to the sealant I usually use, but most write ups stress the need to do the multi step prep like clay bar and polishing, especially the first time. I know prep is better and will make for a longer lasting finish, but is it a total waste to skip all the prep and go straight into ceramic spray directly after a simple wash? All I need is the coat to last like 4-6 months.

My car is old and I'm lazy and not rich, so I won't spend all day prepping or $1000+ for a pro detailer. I just need to know if it's worth it to switch to ceramic spray or if I should just stick to old reliable sealant. I don't need a showroom finish. I just need an "ok" level protection and water repellent coating for a few months.

If you've used ceramic spray with zero prep work, how did it work out for you?