[tharkun__]

Some of this might be great advice and the reasoning sound. Some of it I can't tell but the thing about water and salt makes me suspicious.

I suppose you mean to add salt after the water boils instead of at the start? Why would the water boil faster without salt with any significance to cooking?

I looked it up again and apparently

    The temperature needed to boil will increase about 0.5 C for every 58 grams of dissolved salt per kilogram of water

One teaspoon of salt is about 6 grams. So let's say 10 teaspoons of salt to increase the boiling point by 0.5C for a liter of water. I guess you will boil about 4 liters or so for your pasta? So 40 teaspoons or about 240g of salt to raise the boiling point by 0.5C.

How long does it take a regular stovetop to heat 4l of 100C water to 100.5C?

The good enough answer to that is that it's not noticeable for you even if you had wasted this much salt on your pasta or potatoes or rice or whatever. Never mind that nobody would/should eat this food any longer as you've just cooked your food in saltier than ocean salinity level water. With the proper amount of salt it would be even less noticeable of a difference. Less time than it takes you to get the salt and put it in.

[norrius]

I suspect this is more about giving that almost-boiling water more points where it can break tension and start forming bubbles. So it doesn't make the water reach 100° faster but makes it more visible.

[tharkun__]

I'm not entirely sure how you mean. Would you care to elaborate your point?

Just to make it more clear, in case I wasn't, the 'common wisdom' as also perpetuated in the parent's statement is indeed about the faster boiling time. It's all over the internet too (and youtube).

The 'problem' with it is that it it is actually factually true. That water will definitely boil faster without salt added to it at the start. It can be calculated to the T if you know all the input parameters, like initial temperature, power output of your heating element, amount of water and salt. The fact remains that it's only by maybe milliseconds for common water and salt amounts used in cooking. So pedantically, whoever mentions it, is right, but it doesn't matter and is not how it's commonly referred to. It's more used to throw around your knowledge about cooking, giving 'tips' etc. I don't doubt that many of the other 'common wisdoms' of cookery are similarly unfounded if pedantically true. Not all of them probably.