Image Trace Raster to Vector Poor Results

Newbe question;

I have seen some post recommending to save an image file as a template, create a copy and trace with the Pen tool. However, this post was a few years ago.

Has Image Trace replaced this method?

In an attemt to convert some line drawings (Wiring Diagrams) to vector files the results have been pretty bad. I have tried using the tools in Image Trace to clean up. However just not getting it done.

Can the majority of JPG images be converted using Image Trace?

Thanks