The decision to update your on-hold message depends largely on the content you are sharing. If you are sharing content that includes short-term promotions, this information will need frequent updating so consumers are always aware of the status of any offers. However, if you’re only sharing general information about your standard products, your operating hours and location, then the decision to update the message can be more reliant on metrics.
However, if there is no other option but to place your customers on hold (perhaps during a busy season), you need to make the experience as pleasant as possible.

You will most likely run into the typical Stalingrad-esque repeating messages that state how important your call is to the business. It is only slightly less annoying to have some form of default music that plays on a loop, and gives you the virtual experience of being stuck in an elevator, listening to muzak ad infinitum.
It's a panoptic experience, being on hold while listening to someone singing about being on hold. Depending how long it takes for someone else to join the call, you could be listening for awhile. The music builds as time goes on, culminating in a spoken verse that begins: "Well, let me tell you all a story / about a man who was on hold all day..." This unusually self-aware song is the default music for a conference call service called UberConference, where "I'm On Hold" plays on a loop for anyone who calls in early, on almost every call that doesn't start exactly when it's scheduled to (or doesn't ever start at all). It's selected by nine out of ten call organizers, and plays over a million times per month, says Craig Walker, CEO of Dialpad, owner of UberConference.