Hex-stocking by transfer/bleed-over

tl;dr: populate sub-hexes with things linking to neighbouring hexes

I am working through HexCrawl25 but this could work for any hexmap set up with hexes and sub-hexes. The basic premise is that things do not stay contained within their hexes and you can find signs or links to hexes straying into their neighbours.

Dicegoblin had a similar idea - Play Fetch: Linking Hexes Together With Adventure Ideas - though they were thinking of more explicit 'links/hooks' as a treasure trail, I am just thinking of 'intrusions/connections' not necessarily active adventure hooks.

Original shower inspiration notes

With a hex split into 13-19 subhexes depending on how you count the subhexes shared with neighbours, this concept gets you ideas for filling eight of them or 40-60% which is very handy for when you might have a lot to do.

Conceptual slapped together w/ Hexkit + powerpoint

I find it is also handy as a way to think a little more deeply about the hex themes - how do they manifest, how might those elements move around, how do they interact with the neighbours? For one of the hexes, the thematic element is the harpy coven that live there - they became the dominant factor and all the bleed/transfer elements in that hex became 'how do the neighbours come to trade/serve the coven' while their presence out-of-hex manifested as either allies dwelling there or defensive measures against predatory harpies.

For another hex, the key theme became the poisonous things cultivated by the goblins dwelling there - the goblins themselves hid and stalked and were not very overt so the bleed/transfer with others both within and without that hex was themed around how others came to use or fall foul of the poisonous bounty.

You could run this a level deeper if you wished; using the Landmark, Hidden, Secret framework you could have either of the less visible elements (Hidden, Secret) be a tie to a neighbouring subhex. Here you would be choosing from among options since you'll have two slots to fill and six options but pick your favourites - or use whatever even better idea occurs to you.

I think this concept is best used as a 'floor setting' idea - these generates a bunch of ideas for sub-hexes within a hex or elements within a subhex - use them if you have no better ideas. Frequently I find doing an exercise like this which generates a bunch of prompts either gives you gold directly or gets you into a creative vein where you reject the ideas because they do not feel right - following that 'why does this not feel right' feeling will lead to better ideas - and your sub-hexes get populated that way.