Originally Posted by
Traveler
This ^!
Backpacking tends to be an evolutionary endeavor to increase gear effectiveness and reduce weight. Having been in the "out of space" position more than a few times over the years I have learned before discarding a pack that fits and travels very comfortably, I will spend some serious time going over my gear. Spreading out one's gear to look at it in entirety does not happen often and engaging in the sorting process is a bit of a chore. However unless one does this periodically the accumulation of stuff can be quite surprising. Using a simple sorting scale of "When was the last time I used/needed/wanted this item" with each bit of gear, regardless of size and weight, one can probably find more room.
For example: I used to pack a wind breaker and a rain jacket which takes up space and adds a bit of weight. I found a good, ultra light rain jacket that doubled as a good wind jacket, eliminating the singular use garments and their related stuff sacks.
My tent at the time was fairly bulky by today's standards but at the time of purchase was one of the better/lighter available. The tent was about a decade old and was at the point micro holes required constant attention. With the age/condition of the tent and advances in tents reducing both size and weight, it was a good time to replace the tent. The additional space this created in the pack just doing this alone was worth the effort and cost.
I was surprised by the number of stuff sacks I was using to hold a variety of small to medium sized things I wasn't using much if at all. Stuff sacks typically do not necessarily fit closely with other pack items, allowing unused void space in packs, so I dumped them out to find all sorts of things I hadn't used in years but faithfully carried with me. I reduced my stuff sack use to that opened up some useful space.
Small stuff seems to grow unchecked - I found a slew of items I had forgotten about, 2-folding knives, Leatherman tool, large screwdriver, several spoons, spare grommets and a grommet tool (vestige of the old canvas and wood frame pack days), a first-aid kit in a small box that had never been opened, a variety of small fire starting tools and other brick-a-brac hikers tend to collect along the way and over the years on the trail or impulse purchase items from stores. These all sound very small and they are, but each one takes up some room, adds some weight, but provide little to no value (in my experience) except to hide in plain sight. Removing this stuff and their stuff sacks dropped weight by a good half pound or more and increased storage space.
Between gear reduction, replacement of a few things, and packing technique improvements, I found my trusty pack was able to easily manage the contents and saved me from having to upsize.