What factors have been considered in determining whether to increase a defendant's sentence based on a prior serious felony conviction?

^3. Sanders served a prison term on all the convictions underlying his eight prior prison term enhancements except his 2005 possession of drugs conviction. This resulted in the court not imposing a prior prison term enhancement based on that conviction. The court also did not impose a prior prison term enhancement based on his 1992 attempted first degree burglary conviction or his 2000 robbery conviction because those convictions were used to impose two serious felony enhancements. (People v. Jones (1993) 5 Cal.4th 1142, 1152-1153 [sentence cannot be enhanced for prior serious felony conviction and prison term served on that conviction].)