I know it's kind of spit-balling, but I tend to use a typical jump of 20-23 ly when looking at straight-line distances to see how many jumps there are. Then use 1 week recharge times. This is my way of making sure they jump to stars they get the best charge times out of.
If I'm not as worried about quick recharge times, then I'll up the typical jump to 25-27 ly, but increase the recharge time to 9 days. This makes for a more straight jump line, but you end up paying in the recharge quality of the stars you jump to.