Here is a native that wants to help you 
It is mostly used when one thing is happening after another. However in this case you also use "and " in English, not always "then"
e.g.: Kahvaltı yapıp evden çıktım. I had breakfast and left home. OR I had breakfast and then left home . (even if you don´t use"then", you know breakfast was the first action)
You can also understand that two things are not happening at the same time if you swtich the position of "-ip"
i.e.: Evden çıkıp kahvaltı yaptım. I left home and (then) had breakfast. (obviously I did not have my breakfast at home)
The thing confusing you is that we also sometimes use it for spontaneous actions!
Although "-erek, -arak" is more suitable in this situation, "-ip" is also used!
e.g.: Mısır yiyip film seyrettik. We watched a movie while eating popcorn./We watched a movie and ate popcorn.
OR
Mısır yiyerek film seyrettik.
I wonder if the information above only depends on you having been speaking the language as a native for 23 years, or it is from books used in general education curriculum, reliable sources, linguistic articles and so? Can you cite some sources supporting your point?
