I've used triggers since they first appeared in HSFX, this was in version 7.0.3 and I've been using them ever since, discovering their benefits as well as their limitations. I've gotten to abuse them profusely in some online missions, getting all kinds of problems, although this was when I was just starting to get familiar with them. For example, in a two-sided dogfight mission on Mixx's beautiful Kalkin Gol map, I chained numerous triggers back and forth from planes from both sides that appeared as the humans approached the border line; in turn, these flights stepped on other triggers, and these then others. On that occasion I added so many flights that the mission was a complete disaster.
As Vonofterdingen mentioned, the trick so that a spawning plane doesn't cause a stutter, is to place a plane of that specific type at the furthest point from the start of the mission, placing two waypoints at a good altitude on the same edge of the map. Recently I have given this type of flight an extra utility, and that is to function as a title trigger, like the ones we can see in the initial videos of a campaign. This is achieved by calculating the times very well and doing many tests, with small consecutive text triggers, that this plane that we have placed there will go stepping one after the other. In this way I have managed to make an introduction to some online missions that we have flown in Squadron 69 at the end of last year based on the French campaign in Madagascar. I have calculated the time it would take for the entire group of pilots to be in the air and heading to the objective, and considering that the trip was long, at ten minutes or a little more after the mission began, and when everyone was already on their way to its objective, the titles began with "Welcome to the Madagascar Campaign", followed by an introduction to the campaign, and then accompanied by the corresponding credits (creators of the campaign, in this case my colleagues E69_PILILI and E69_LEZOS, being me only the converter of the campaign from the HSFX to the BAT). This turned out to be very useful and entertaining, as well as giving an extra point to the introduction and the theme of the campaign.
In one of the missions, a plane of French refugees fleeing Madagascar had to be escorted, but these refugees first had to reach the airfield and board the plane. I achieved this with a first trigger that started a bus that traveled through the center of a city, and that when it reached the head of the aerodrome runway, it generated the appearance of an old French plane with few passengers, which started its engines and took off. Many other triggers had generated a whole front of British armor advancing towards the airfield from the north. The times were very tight. The humans had to hurry to give air support because the refugees were about to take off, and enemy armor and vehicles (which had to be stopped or destroyed) were advancing dangerously towards the airfield. Adjusting the large number of triggers that make up this mission took me many days of work, but finally the mission was a success. I mean by this that the possibilities that triggers provide are extraordinary, it just depends on using them creatively.
Another example. This was a very big challenge for me at the time, and I did it entirely in HSFX for the first time, successfully, and last year I got even better results with BAT. Several years ago I was working on a mission to capture Fort Eben Emael with German gliders. Trying to stick to historical facts, I needed a way to represent the blowing up or dynamiting of one of the Albert Canal bridges by Belgian forces to hinder the German advance. With some license I used a bridge in the Maastricht area (don't ask me what map I used, I don't remember, I know I had to build Eben Emael from scratch, walls and all). I racked my brain for days trying to figure out how to blow up a bridge. I finally got it, with triggers of course. I was able to repeat this action in an online campaign from Korea that was flown in my squad in 2021, where the American forces (humans) had to rush to eliminate enemy engineer columns that were about to blow up the bridges over the river, in Seoul . Both the engineering columns and the dynamiting mechanism were executed with triggers.
Now you want to know how the damn bridge is dynamited. In this last case, the column of engineers advanced through the streets of Seoul, between columns of smoke. Humans had to detect and destroy them, which was not easy, because these vehicles were moving in a zig zag to avoid being detected. Upon reaching the base of the bridge, the enemy engineers activated a trigger to spawn a Ju-87 Stuka with a 500 kg bomb (now I don't remember if it was exactly 500 kg or if it was a bigger bomb, but to exemplify the dynamiting mechanism is enough, then you will do your tests; keep in mind that the bigger the bomb, the more the destruction of the bridge is assured, especially if it is a concrete bridge). At the moment of the explosion, the same trigger that activates the "bomb" sends a message that the engineers have achieved their goal and that the humans have missed theirs. Well, the first Stuka waypoint should be placed two meters below the bridge, very close to one of the pillars near the shore, and the second waipoint should be placed about five meters further, at an altitude of " zero" meters. You'll need to edit this manually and check that it stays that way. This ensures that the Stuka immediately appears and crashes without being seen, as it is under the bridge. As expected, the bridge is destroyed on the spot.
In the following video you can see an example of this: the first explosion is activated by some vehicles, the second explosion is activated by a train:
https://youtu.be/fVOzqnuyKLEA variant is to place red artillery (for example) within a blue environment, to represent sabotage or simple dynamiting of facilities. Artillery is activated with a trigger:
https://youtu.be/g7jBDVZgbZ4At the moment I can't upload examples of the missions because I'm away from my computer for an indefinite period of time, taking care of a family member in another city. But as soon as I can I will publish missions with these examples.
Kind regards and good missions with triggers!!