In version 17.23 I found that the GPS paths started to become more zigzaggy, even though I had configured All System + Multiband. I found that all activities have Extended Power Mode set at the start. In the settings for the activities (e.g. Walking) I set to Max Accuracy as default. This setting was then the default at the start of the activity. After a few activities, however, it was set to Extended again, even though Max Accuracy was set as the default. I had no choice but to set All Systems + Multiband for all Power Modes. Now the paths are no longer zigzagged.