I'm not bothered about the duration, but if changed then I'd prefer it to run exactly along GE. It will make it easier to stay organised and one gets a 1-day break from each event on the same exact day. Goods and units organisation will come down to a simple choice of priority. Either one has got enough to do both, or, one's guild can tell one which event to prioritise first and from there on will there be no further questions. Because as it's right now will there be frequent inconsistencies in each players' performance when they participate in both events. Running GBG in parallel to GE will also benefit players who change guilds frequently.