Most of the exo planetary systems that have ever been discovered, based on the fact that telescopes look back into the past from incoming light from space and because of the level of tech we have we can not properly view small object in front of massive bright stars
The relationship between planets and their parent stars
https://exoplanets.nasa.gov/resources/1040/hot-jupiter/
And
https://universe.nasa.gov/stars/multiple-star-systems/
As such our tech only allow us to observe what are called hot Jupiters with some systems having 4 or more Jupiter size planets orbiting in close proximity to their stars, which affect brightness intensity or its wavelength
And the main thing we observe the most is system where one small star is orbiting or gravitationally affecting large star ... or 2 mutually orbiting stars throwing off solar willing and siphoning materials from each other
Dont know if this means that many system started like that or if those are the only ones tech allow us to observe