Generally, 108 counts of mantra japam are done. If not possible, the japam mantra is recited 28 times. Even if that is not possible, at least 10 times of japam is done. Beyond 108 times, one can go up to 1008 times. The japam count is not based on one’s wishes and conveniences.
There are stipulations on the number of teertha japam count. Based on the objective of the japam, it is either done 4 times or 7 times. If the stipulation requires 108 counts of teertha japam, then it must be done 108 times.