Old thread got me. No one has mentioned it but it is dependent on the exact insulation.
Down should be stored in the storage sac to maintain loft. In a humid environment you need to do something to prevent mildew, etc if you are going to store in totes.
@Buffalo-Jo assuming down insulation use the biggest tote you can so the bag is as lofted as possible.
Synthetic comes in hundreds of different versions that are legitimately different. Many of them are stacked sheets of insulation that, once the sheets pull apart, lose insulating value. So some manufacturers use glues to hold the sheets together. Washing and simply packing/unpacking the bags breaks down the glues as well as breaks down some of the insulation material, dramatically reducing loft and insulating value. Other types of synthetic dont use glues at all and rely on the shape of the fibers for loft, these usually last longer and will handle washing better. But in general synthetic doesnt last as long as down and can have some different things going on. Some synthetics can be stored fully compressed for instance without issue, and packing/repacking does more damage than simply leaving it stuffed does.
Bottom line, ignore any advice that isnt specific to YOUR specific insulation. In all likelyhood it’s good advice but on the other hand it could very realistically be totally off base because its for a totally different material.
Here’s a suggestion: What does the manufacturer recommend? Maybe start there. Outside of an Amazon-only or bargain basement manufacturer, they chose that insulation for a reason and they know what it takes to maintain it a LOT better than random dudes on the interweb do, and they’ve gone to the trouble of providing you specific guidance ahead of time. If they included a storage sac theres a good bet they want you to use it. Manufacturers dont generally give you free stuff just for the heck of it. In the specific case of the OP’s bag, note they are recommending keeping it lofted, keeping it dry, reducing agitation during washing, and using a specific soap, low heat, etc…all of which are designed to make the insulation last longer.
