Tests
On the last test, it is best to engage the slide lock and test for hamer drop by whipping the pistol muzle downward rapidly, adding inertia, as you slip off the slide lock.
If the hammer stays cocked through three of these violent tests, the engagement is safe. If it does not stay cocked, you need a gunsmith who can do a trigger job. Under service conditions, you have to rely on the integrity of engagement and you can't baby a pistol.
One further test not mentioned (I'm shocked) is to cock the hammer over an empty chamber or a snap cap (your choice) and pull back slowly, s l o w l y, for about half the release. Place the pistol next to your ear and touch the hammer spur. If you hear a very faint click, you need a gunsmith who can do a trigger job.
Both of the above are beginner's failings, and no experienced pistolsmith would let a pistol leave his shop with the above faults. For example, if you are told that you have to hold the hammer back when you drop the slide on an empty chamber, take THAT gunsmith off your list. He does not know how to do a trigger job. If your street pistol has been modified and you detect that the hammer hooks have been "lowered" i.e., filed down. Replace the hammer and find a gunsmith who can do a trigger job. All of the above are even undesirable on target only pistols, but they can be suicide on a carry piece.
A good pistolsmith can do a trigger job on a Series 80 pistol that does not have the characteristic feel of the firing pin safety releasing, does not have to "lower" the hammer hooks and the hammer will stay cocked under the torture test described above.
Some gunsmiths will whine and tell you dropping a slide on an unloaded chamber will do damage to your pistol. And, this may be true of their output, but if it will not pass the test, it is not safe to trust your life to that weapon.
Followdown is a SYMPTOM that will always get worse...
I was in the US Army Ord Corps during the halcyon days of the 1911, and I have worked on more 1911 pistols than most gunsmiths... and every pistol I worked on received the above described test to determine that there was no followdown. In all of the Army service and earlier and later gunsmithing work, I have never put a pistol into somebody's hands that I would not personally carry for defense. And, I know many pistolsmiths who feel likewise. You may have to learn a lot more than you know now to perform satisfactory work, but if all of us could do it, certainly you can do it. NEVER stubbornly defend a stupidity because you don't understand the mechanics involved. LEARN. There is adequate literature out there to inform you.
One last thing: Boosting a trigger, i.e. applying pressure to the hammer by leverage or direct pressure will tend to straighten out a sloppy trigger job, but it says volumes about the slipshod methods of the perpitrator, Brownells "experts" be damned. They sell the proper tools to correct the angles without straining the mechanism; use them, don't rely on "field expedients" in the shop. You may have to use that trick in the field someday, but the parts should be changed for new ones the first time you are back in the shop.