Live track - battery life/adjustments?

I used live track all the time and I do not notice it has any effect on battery life. It might have some minor effect on the battery of your phone. I have done running events of 20+hours and using live track the watch still only uses 2-3% per hour. So I would not worry about it. 

Exactly as Bernie wrote...

Yes what I heard about was phone battery - I don't want to destroy my phone battery life...

After years of livetrack using, never noticed any impact on my phone battery or on my data plan (back when that was still costly and limited), the amount of data the phone sends is small.

Hmm interesting. Good to know! I'm tempted to still maybe doa  trial with it though because I worry especially with spotty reception, it'll try and get the data out and use up the battery more aggressively...

Bad/intermittent cellular reception does make the phone use higher power part of the time. So it's indeed not a bad idea to test LT in the same challenging circumstances as you plan to do the long-duration activity in.

If you really want to minimize phone use, you could do a trial during which you start with LT on as usual for 5 minutes, then switch the phone to airplane mode for 10 minutes, switch it back to normal online mode for 5 minutes, etc, then check if that still updates your position on the LT map at these intervals.