You may not hiatus through more than one Activity Check in a row (which, again, means your hiatus should not exceed one month at a time barring mod-approved exceptions).
During a hiatus it's generally assumed your characters are going on autopilot (doing their usual day-to-day routine, whatever that might entail.) or you may assume they've gotten lost in the Isles, they fell down a warp pipe and are having a marvelous adventure somewhere, or are hiding in their room, or are communing with nature and getting married to a tree. Almost any excuse is fair game, however players are responsible for making any arrangements about handwaved actions taking place during hiatus, and responsible to talking to their fellow cast mates or plot mates if their absence will affect anything.
It's not mandatory, but (HIGHLY RECOMMENDED) you may also announce your hiatuses and drops in smash_ooc as a courtesy to your fellow players (don't forget to use the drop/hiatus/slowatus tags!), but only posts here will save you from getting a GAME OVER.