Yes, good after 24 hours is if it is a good sounding cable. Horrible if it is something like High Fidelity cables. Sometimes I let my beta cables burn in for five days. If they still sound bad or wrong, I indicate that. If it turns out to be an excellent cable, it sounds "good" or excellent after 24 hours of burn-in. You just have to nit pick everything I write.
As to the Black SR fuse, I have several systems I used them with. Unfortunately, after the initial 10 to 12 hours of enjoying the significant improvement compared to stock fuses, they haphazardly sounded wrong and not musically enjoyable until the 72 hour mark. It happened on three systems. Maybe your mileage is different. I am reporting what I heard.
As to not wanting to wait 500 hours for a cable to burn-in, I am sticking to that. It’s my choice not to have to wait 3 weeks of continuous signal passing through a cable to be able to enjoy it (those High Fidelity cables had several months in my friends system).
I was at a HEA audio salon meeting and commenting on how horrible the Magnapans sounded (3.7 and 20.7). I heard the 3.7 sound excellent (another pair) there previously. What the store owner failed to tell us is that the speakers were brand new and not broken in as well as the Shunyata cabling. Yuk, what a messy sound that was. Yes, speakers require a break-in period which can be significant. Funny that sometimes they do not require more than a cartridge breakin time before they do sound excellent. It is component/speaker/cable dependent.