Explorer Count / %
I have 31 dwellers total. At any given time I have about 6-7 out in the wastelands. As I train my dwellers stats to higher levels, I am moving towards having 7-8 exploring at once. That's around 25%, growing toward one third, of my workforce exploring.
Exploring Summary
I generally give them 6-7 stim-paks and 4 rad-packs. Most explorers make it for 6 or 7 hours before I have to recall them and they have maybe 15 items on average, most people weapons that do a maximum of 7 damage and outfits that add 1-3 points to a few skills. Maybe one out of five explorations results in a great item.
One guy has max endurance and he stays out for 12+ hours. Also, one guy just picked up a bazooka looking thing and he's been out for 12 hours and still has 8 stim-paks left. In hopes of getting rarer loot, I'm considering making a change and sending out luckier people for short explorations instead of stronger ones for long explorations.
Question
What are the signs that I should send out more explorers?
Best Answer
From reading discussions on Reddit, the general feeling at the moment is that explorers meet more difficult challenges and find better items the longer they're out on a particular journey. As such, it's not so much a matter of how many explorers you should have out as it is how many dwellers you can train up and equip while still being able to maintain your vault. There also seems to be a special opportunity that comes up after 60h of exploring (but can be passed or failed).
Also, it's not just endurance or luck that help out. All stats seem to have some impact on how the explorer deals with events (e.g. unlocking a box, healing a person), so you should train explorers in multiple stats. The better your explorers' stats, the longer they'll be able to stay out and the more successful they'll be.