I wrote my entire EPQ essay over a two day period earlier in the year, while updating my production log and presentation as I went along and I'm fairly sure I've achieved an A/A*. It's very much possible if you take interest in the topic you're researching. Just remember to reference as you go along as that's what takes the longest amount of time. (I'm aware this is probably too late, but for future reference for those thinking of studying EPQ.)