My inclination is that the packing inserts would work well for particular packing requirements/methodology that I just don't have.
I'm always trying to be organised but I'm often changing my "pattern", trying to improve things ergo I am not organised because I can never remember how I packed things
this time (a slight exaggeration - there are elements of this but there are some consistencies too).
I cycle-camp and tend to go heavy rather than light and so my luggage/packing requirements go beyond a change of clothes and some electronics. I try to organise my panniers into "rooms" so that I have a sleeping/bedroom pannier, a cooking/kitchen pannier, a clothing/wardrobe/electronics pannier and a food/pantry pannier. Accommodation (tent), stool, waterproof cape and crocs go on the rear rack. Often I modify this on account of space needed, weight distribution and variations in stuff taken.
Stuff that I might need on the move goes into the large internal "organiser" pockets in my rear panniers (this includes 1st aid kit, toilet trowel/paper, fruit squash for the water bottle, bike lock & snacks). My bar bag has my powerbank, charging leads, camera, binoculars and whatever odds & sods I might need that will fit.
I've attached some pictures of the pocket of my rear pannier - it is external to the main drawstring closure compartment but covered by the main "lid" flap. It has an internal flap that has organiser pockets on it. They're quite big pockets but I'm not sure that this shows in the photos (11" x 9" and 3" front to back at the top, tapering to 1½" at the bottom)
A fair bit of my stuff would be too big and bulky (e.g. big sleeping mat & Trangia) to fit nicely into one of those inserts or would not make the best use of the available space if it did go into one.
I use a combination of rubble bags, Exped drybags (clean & dirty clothes), nylon bags/pouches (electronics, sewing/repair kit, 1st aid kit) and assorted plastic bags - usually good strong freezer bags (usually for stuff that I don't want to contaminate other stuff, or for waterproofing). I always have a roll of pedal bin liners for rubbish and other uses.
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