How do you approach testing a new offer category you have never run before?

I have mostly worked in one vertical and I am thinking about whether diversifying across offer categories would reduce overall risk or just add complexity.

For anyone who has crossed verticals: how much of your existing knowledge transferred and how much did you have to relearn? Did you use the same traffic sources or find that different categories work better on different networks? And how long before you had a real read on whether the new category was worth continuing?

Also curious whether you approached it as a formal test with a defined budget and success criteria or more exploratory at the start. Trying to figure out the right level of structure for something genuinely new.