These can be quite difficult to reassemble for someone who's never done one before...including folks who routinely take apart and reassemble watches :unsure:.
Since this is basically a "Full Plate" design, almost every part has to be fitted at the same time. Lining up all the pinions in the holes correctly takes a lot of time to get them seated right. It's actually more similar to reassembling a clock movement than a watch movement, as most watch movements have some sort of bridge or 3/4 plate design. This allows for assembly in stages an not all at once.