Unsure about job change-career break option?

[Hubbabubbaisyummy]

I am in a job that has been good for me for many many years. I don’t hate it, I am just bored, the same things over and over…I have not applied or interviewed 15+ years, and this makes me insecure. However I am ready to move on (I think). My biggest worry is: am I applying for jobs that might be worse or not? And wether I might regret leaving.
so here is my question really: why don’t people take unpaid career breaks in Job A to “try out” a new job (Job B) they might be offered. So for example: request career break in Job A for 6 months, while you try Job B, and then you decide which one fits best and give your notice at the other? Seems less stressful as there would always be a plan B?
not being unreasonable = keeping Job A (unpaid career break) and B going seems like a great idea
being unreasonable= you can’t do that!!

What is in it for Company A? Presumably you'd have to get permission - they'd find out when your tax code got updated; or your LinkedIn, and it'd be a pretty big secret to try and keep...

I can take a company break with 5 years of service, but it's for time off or travelling, and forbids other work. I'm not sure if all contracts are similar in that regard but I can't imagine any company would be thrilled with the idea of keeping you on payroll and holding your job for six months while you work somewhere else and decide if you like it.

It's also risky for the new company - if they figured out you were still employed at Company A, they'd know you had serious enough concerns about the job being right and were keeping your doors open. That makes you quite risky in their eyes. It costs money to hire, they'll want someone who is invested in making it work.

It's usually against the career break policy to take paid employment during a career break. I think you could volunteer though.