Is there a bad time to submit to an agent or publisher? eg. when it's only a few weeks before Christmas are agents and publishers extra busy?
If an agency or publishing company knows what they're doing, they'll have a log of what manuscripts come in when, so Christmas downtime won't mean that your manuscript will get lost. It will, however, mean that you should probably allow more time for it to be read - say, four extra weeks. This is not because everything slows down - I always go full-tilt towards Christmas and I'm waiting for the year when I can lazily read submissions in the Yuletide season, but I doubt it will happen. No, it's more because we all shut down for a week or so, collapse in a heap and then spend half of January trying to get back to full speed.
However, the timing of my submissions to publishers is affected. I'm about to send maybe one last submission for the year and I'll probably put it on ice anyway, because the Acquisitions meetings are about to stop for a month or so. If I send out something now and it doesn't get looked at, there's a chance it will get lost on someone's desk amongst all the covers to be signed off and pages going to the printer before the printers close for the year. I'd be better off waiting until the new year. This can be frustrating for my clients, obviously, but people start taking holidays soon and those meetings don't happen without key people being present.