From what I read, initially the Soviet "illegals" programs were successful. This was before the Cold War and during the early parts. After that, it was less successful and often viewed as a waste of resources.
If interested, I recommend "The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB".
There was a post-Cold War defection of an individual (Mitrokhin) who worked for the KGB in their archives and provided a large trove of intelligence. A researcher (Christopher Andrew) collaborated with him to produce 2 books, which included a large amount of data about the Soviet "illegals" programs.
It's often going to just be more effective to bribe and blackmail people with access, rather than hope your illegals have successful careers and gain the right access.
> There was a post-Cold War defection of an individual (Mitrokhin) who worked for the KGB in their archives and provided a large trove of intelligence.
The article refers to that; in fact it's how this agent was identified:
Barsky had in fact been trailed for several years
by the FBI. His name had been discovered in files
copied from KGB archives by Vasili Mitrokin, an
archivist who walked into the British embassy in
Riga in 1991 to offer up his secrets.
If interested, I recommend "The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB". There was a post-Cold War defection of an individual (Mitrokhin) who worked for the KGB in their archives and provided a large trove of intelligence. A researcher (Christopher Andrew) collaborated with him to produce 2 books, which included a large amount of data about the Soviet "illegals" programs.
It's often going to just be more effective to bribe and blackmail people with access, rather than hope your illegals have successful careers and gain the right access.