I have had the same experiences when adding CT-1 and/or CT-1U interconnects and speaker cables to my system. I now have 2 U interconnects, a U speaker cable, and regular CT-1 for phono signals. It seems the speed, treble extension, and detail are there from the beginning, but the immediacy, body, bass, warmth, and dimensionality take a while to develop. I also noted my system gain seems to improve upon break-in.
I have been somewhat reluctant to try HF power cables as I only have one place that can use an IEC connector: my Manley Steelhead phono stage. My amp and preamp use a special round military connector and I am now using some Intuitive Design Power Bridges that were a big improvement over other power cables I have tried. I also have a Power Bridge on the Steelhead. I thought about trying an HF power conditioner to plug all of my power cables into but these take the big bucks. I think at the moment that I am more inclined to keep upgrading the IC's and speaker cables.
It seems so far from what I have read on this thread that the PC's are somewhat of a mixed bag, some seeing little differences and some after an extended break-in, but I am wondering whether they are of the jaw-dropping improvements I have heard with IC's and speaker cables.