One reason I am no longer so hot on assassins. Picking off generals inevitably causes some new generals to get adopted in their place, and talented ones at that. So what happens is that the faction actually grows stronger from being rid of its mediocre/awful family members and acquiring some talented ones.
Yes, that does happen on occasion. Sometimes it goes the other way if you have a talented enough assassin. Get rid of that 4 or 5 Star to see him replaced by a bureaucratic type with no battle skills

I've got another one....the "double the garrison in one turn because it's the next city on the to-conquer list" trick. I've seen this one on more than one occasion so I won't give any campaign specifics. They didn't come from outside the city because I had all roads under observation by spies or blocked by converging armies, and they weren't brought in by fleet either because the city was landlocked, or if coastal, the port was blockaded.

I guess the city guard must have recalled their ranks from the local pubs and brothels