Most useful tweaks that are sensible and really make a noticeable improvement

I've been using Herbie's tube dampers for several decades on 12AX7, 12AU7, 6SN7 and 6DJ8s.  They have no negative effect on the sound and the sound is better with them on.  I have also used a pair of tight rubber/silicone rings from Sandy Gross from years back.  They made stock cheap EI 12AX7s sound more like NOS Sylvania large D getter 12AX7s in an EAR 864 phono stage (without the rings-yuk).

Paint both sides of an fo.Q RS912 turntable mat with 2 coats of AVM (anti vibration magic). Unfortunately AVM is no longer commercially available, but I obtained 17 bottles of it 3 months ago, by asking around. It was semi-solid but I managed to revive it by mixing with water and squeezing it until it came back to life.

Said fo.Q/AVM mat adds incredible inner detail and depth when playing LPs and 45s.
If anyone has spare AVM stock for sale, contact me and I will buy it at full price if it's still liquid. Must say "Made in Canada" on the front of the box. If it says "By Uniko" on the front, it's old stock and probably solidified.

If you can’t afford fancy fuses, wrap the middle of an ordinary fuse glass with a 5mm strip of piezoelectric tape, then paint the tape with everyone’s favourite graphene paste.
Assuming you may already have leftover ingredients on hand, the cost = $1 for fuse + 30c for tiny strip of tape + 20c for tiny TC smudge = $1.50

E=fo.Q+TC²

“Seems to me actual real tweaks really are those that make sense.”

No, no, no! It’s actually the opposite. The best tweaks, anyway. People need to be a little more open minded. I’m not suggesting they be so open minded their brains spill out on the floor. Break on through to the other side!

With all due respect, Geoffkait do you ever sleep? Broke thru to the other side eons ago. Thankfully found my way back. Senseless tweaks are snakeoil designed to part the gullible from their available funds. A fool and his money..........! 
Now that's not to say that an unconventional tweak could not be worthwhile.  Let's take Geoffkait springs, unconventional yes but a possible sensible tweak. Would I buy before try.......no but with a 3 month money back, no question asked return policy sure why not.
I would even buy at a sensible cost which his springs are not.
Tweaks must make sense.
Ps. Did you know rubbing bacon grease on your cable ends or connectors will eliminate any sibilance in all applications?