I think over fixing would be pretty hard.
So you can't change the times on the machine? Can you change the temp? Higher temp would mean shorter times. Or lower temps longer times.
The Fuji stuff I use fixes and bleaches in much less then 8 minutes. At normal temps 35-40C Fix is a total of less then 2 minutes. Bleach is one minute. Even with those times I fix and bleach longer to be safe. I can see the bleach being different enough for the time difference but isn't all the fixer more or less rapid fixer? 8 minutes sounds like a long time to fix with rapid fixer.