Welcome!

There are not any rules try what you like that is what we call experience.

In my warm water fly fishing here in OK I generally fish weighted flies on 6wt to 8wt rods. I use a 3 section hand tied leader out of cheap spooled mono,60%(of the desired total length) is the butt section, 20% middle and 20% is the tippet. In this heavy leader case it steps down in lb test from 30 to 20 to 12. Each step down in leader strength(lb-test) should be in the range of 50% to 67%

A warm water leader for a 4wt or 5 wt rod might step down from 20(lb test) to 12 to 6 .

With weighted flies you can get by with just a straight section of mono as a leader,but I feel you have better control to hit tight spots with a tapered leader.

Air resistant bugs will cast better on a tapered leader,and may be near impossible with straight spider wire because it is so soft.

Good luck