The evolution of Et to & is very similar to how minuscule letters were developed. Think about the steps it took to get from A to a, B to b, D to d, E to e, F to f, G to g, H to h, N to n, R to r, etc.
I have a feeling the ampersand did more than save space-- it saved you using up all your lowercase As and Ns, which are very common letters; the frequency table for English goes E T A O N R S H I, and after that, I forget, but I’ve usually figured out the Hangman word by then, so no need to memorize further.
The ampersand was developed when writing was all handwritten. They needed to save space and time but they weren’t using type, so there was no risk of running out of particular letters.
In fact it wasn’t even more popular in the pre-press era than it is now.
I’m pretty sure this is the history of the ampersand.
That’s how I’ve always done it but I thought it was an upper case sigma and meant to represent summation, basically, a plus sign.
- and & (concatenation and concatenation)
I never learned how to draw or pronounce the concatenation symbol either. In fact, I’m not sure that I’ve /ever/ heard it pronounced, or /ever/ seen it drawn.
I use the symbol on the keyboard quite a lot, when working with computer languages that don’t support + string concatenation, or that don’t support operator concatenation at all 
Also, whatever the Latin derivation of the Ampersand, the /character/ &, which we mostly agree is not used in handwriting, is a German character for the German word ‘und’ (‘and’), because the English got their original printing fonts from the Germans. (Ye Olde Fonts).
But…but… on Wheel of Fortune L is the next consonant! Not H!
It WAS even more popular …
All kinds of crazy sigils (besides &) visible, eg here:
This is clearly not somebody’s rushed chicken scratch shorthand, either.
In his wonderful book The Bestiary: A Book of Beasts T.H. White* reproduces a piece of manuscript text to illustrate how difficult it is to read if you’re not familiar with them. Not only do they use some peculiar signs, they were given to frequent and often obscure abbreviation. And the clear text itself isn’t all that transparent, either, with words like “minimumi” looking like a stand of identical vertical strokes.
The ampersand is no harder to learn than the number 8. It is the number except upside down and backwards. I handwrite it all the time. I start at the bottom right, go up the top left, come down on the right and then cross my initial line. Anyone who has learned cursive can teach themselves to do it in five minutes.
My ampersand looks like the middle one in the illustration, but with a much smaller loop.
This frequency table gives the order of the first twelve as ETAOIN SHRDLU, which occasionally appeared in newspapers printed by Linotype and other casting machines as “dummy text” that was not caught before final editing.
If you had to meticulously draw each letterform by hand, you’d search for ways to make your work easier, too.
That’s the way I always do it.
Exactly. Nothing to it.
My wife went to high school and college in Ireland, and uses the Tironian note for ‘and’, which looks like a ‘7’. (Several examples can be seen in the picture in post 7.)
The frequancy table I learned when I was in grade school starts ETAONRISHDLF.