If I remember correctly, the time it takes for an item to restock is about half the time it took for it to empty.
For a runner, the only thing Hawaii has that's worth buying is the flowers so a lot of people probably skip going to Hawaii for the same problem you face. If there are no flowers then there's nothing worth buying. As a result, flowers probably empty slowly so when there are no flowers there are no flowers for a long time.
This is why when I have gone to Hawaii, I'll actually wait for there to be no flowers in stock before I leave. Heard a bit about this issue from people earlier in my short Torn life, plus even when inventory is full abroad I always get there as it's gone, so leaving early (or late) seems to get me there on time. 'There' describes most locations beyond 2 hours, barring SA seeing as sales there are between Xan and other items.
Side question, does DrN calculate the roundabout time it took from being updated as new stock to the time it's reported as empty? It wouldn't be exact, since it depends on updates from the users when they travel, so the timing could be off a bit. However, if items do restock about twice as fast as they went (half as long as they took to sell), could we add an 'estimated time to restock' timer on big items like plushies, flowers and common drugs?
If you fky enough you can guestimate normally at which current stockvalues you can fly to which country and dont have a too big risk of landing without stock. If you leave for hawaii with 300 flowers left... odds are big none are left upon landing
I remember while flying that whenever either Hawaii or Japan ran out of flowers the place turned into a cannabalistic warzone where everyone either mugged or hosped anyone they could. It was just a matter of seconds to get the f out or sit there for a few hours until the flowers came back and everyone calmed down. I always checked travel hub but that was still no guarantee so I hated going to those places.