Volvo Repair: Tranmision oil change., hi line, rule of thumb

Question
Hay Mark another question. 91 740 turbo S/w. (I wrote about shifting problem last time) I did change the oil filter and added oil. I did not do the oil flush with the hi line process. I heard 2 different opinion on changing completely that it may cause a problem with the transmission. Is that true? Even though I already change the filter and oil I like to redrain and do the hi line flush. Is that safe?

Answer
  Marco, boy, that's the question of the century. Two scenarios. One, flushing can remove a lot of debris. Where does that debris ultimately lodge itself? If it's in the valve body, there's trouble. If it all comes out, perfect. Two, if the debris is already lodged in the valve body, a flush may clear it and solve your problem.
   My general rule of thumb is, if it's had regular changes or flushes, keep it up. If it's never been touched, drain and fill. New filter is a plus. How many miles are on it?

Mark