Ike

That matches the gauge. I was expecting worse from the drop and it lines up with about a litre an hour.

On question 3, ethernet is more fussy than it looks and two things matter:

Bend radius. Do not fold it round a corner. The rule of thumb is a bend no tighter than about four times the cable diameter, so roughly 2-3cm radius for ordinary patch cable. A sharp crease changes the spacing of the twisted pairs and that is what the whole design depends on. You will not see a dead link, you will see a link that negotiates at a lower speed or drops under load, which you will blame on your router for six months.

Tension. Do not pull it taut between two fixings. Leave it slightly slack. A taut cable transmits every knock to the connector, and the little plastic latch on an RJ45 is the weakest thing in the run.

Other than that it is robust. It does not mind running alongside furniture, and for a 20m domestic run it does not care about mains cable nearby nearly as much as the internet thinks — twisted pairs reject that interference by design. Crossing at right angles rather than running parallel for metres is enough.

Both things are true and the reconciliation is that frequency is not the variable that matters — total weekly volume is. Frequency only matters because of how it lets you distribute that volume.

When the studies find twice a week beats once, the comparison is usually at equated weekly sets. Same total work, split into two sessions rather than one. The advantage is real and it is modest — meaningful over a year, not the difference between growing and not.

Why it exists: there is a limit to how many hard sets one muscle benefits from in a single session. Somewhere past roughly ten working sets the later ones contribute much less, because you are fatigued and the quality drops. Splitting the same twenty sets into two sessions of ten means more of them are done fresh.

So the rule is not "twice a week is better". It is "do not cram more sets into one session than you can do well".

Adding the identification trick, since you asked how to tell without a gauge.

Lay the old screw on a ruler with millimetre marks and count the crests over 10mm. Ten crests in 10mm is 1.0 pitch, about twelve or thirteen is 0.8. It sounds crude and it is accurate enough to tell coarse from fine every time, because the two options for any given size are far apart.

And never force one that binds. A fine screw started into a coarse hole will cut its own way in for a couple of turns and destroy the threads on the way. That is a much worse afternoon than a second trip to the shop.