Resorting to Google:
"Typically, in a criminal trial, the prosecutor cannot present evidence of prior convictions to attempt to prove guilt by suggesting that the defendant exhibits a pattern of criminal behavior. The issue of prior convictions being used as evidence generally only arises when the defendant chooses to testify."
These convictions might be discussed prior to a charge being laid. There seems to be a change in behaviour once a charge is laid against that person.
Scots law allows consideration of previous proven offences in very particular circumstances. If I recall accurately, particularly offences involving children.
The
Moorov doctrine can be used where a series of crimes have been committed and are closely linked by time, character, circumstance and place of commission as to constitute a course of conduct by the accused. The accused must be positively identified in each case.
Corroboration in Scots law - Wikipedia
en.wikipedia.org/wiki/Corroboration_in_Scots_law