The test mostly covers BS. It has radial engine questions, but almost no small turbine questions. Extensive questions on carbon pile voltage regulators, none on solid state systems. It is dated and has not been revised much. As a practical test for real wold information, it fails badly. Basically, the most valuable item for an A&P is the time spent as an apprentice. The method I suggested is what I used when I took my tests, I got a 98, 94, 92 and an 88 in scores (I took it in 1987).
In reality getting an A&P is a license to learn. When we hire a fresh licensee, he will spend a year doing the simple jobs and playing tool monkey for a much more experienced mechanic. Eventually, depending on his/her uptake, we will assign jobs that are more complicated. Sheet metal is where some get it and some don't. My personal weakness, I can't weld, I'm a melter. I can, on the other hand, troubleshoot a FADEC, install and test avionics and just last week, pull the RGB off a PT-6 and pull the Hot Section for investigation by the FAA. It seems my little gliding experience with the Caravan this month was not a governor, but a Nose Gearbox Failure. It took a bit of troubleshooting to get there. You kind of start with the simple answers and work your way up. It turned out the Hot Section has defects it should not have at 20 hours SMOH. So if the gearbox hadn't failed, the Hot Section would have.
More to the point, not one question related to PT-6 engines on the tests. Not one question on turbine blades. Your A&P license lets you do this kind of work, right out of the box. If the test was valuable, it should have covered some systems and items related to the real world, not Beech 18's systems and carbon piles.
Metal in the prop shaft, there was more in the gearbox:

Coating Failure on the CT Blades, 20.5 hours, tsk, tsk.
