This comment is more of just a mental note / discussion point. It seems that if the only reason to have an offset is to avoid loading issues then it probably doesn't need to be configurable, we could probably just hardcode it to 15 seconds or something like that.

But I think there is at least one other case, which is a multi-page PDF document where the pages are lazy-loaded. While browsing the document, you don't want the UI to have to worry about refreshing the signature every 15 seconds to get the next pages as the user continues reading. It would be good if the offset were sufficient in that case to let the user read through the document while only having to wait for a siggy refresh every 15min (or 5min), etc.

Whether or not we can just hardcode this to 5, or 15min etc... for previews I guess could be up for debate.