I can only offer anecdotal evidence in the form of a personal experience, but yes; I did type in a lot of those program listings back in the day, on my Commodore 64.
My first encounter with type-in programs was with the Finnish MikroBITTI computer hobbyist magazine. Back in the 1980s, each issue featured several reader-submitted computer programs — so-called “program listings”, which were not much more than dot-matrix printer printouts of the program code, scanned and laid out in columns on the magazine pages.
The published programs targeted the popular microcomputers (“home computers”) of the era — mostly 8-bitters:
The magazine paid a pretty good sum for the “program of the month” and handed out smaller rewards for the others so there was a monetary incentive to try get one published.
The published programs were typically written in various machine-specific BASIC dialects. Any other language was a rarity. Usually they were simple games, sometimes utility software. A program listing was accompanied by a brief description of what the program does, how the reader is supposed to use it, and on which lines the major pieces of logic or subroutines can be found. Sometimes, there was further discussion on how one might port the program to another BASIC dialect or platform.
Initially, you had no way of making sure you had typed every character correctly. A small typo in, say, a conditional statement might not have prevented the program from running but would make it behave strangely. You might also not have known how to produce all the required control characters featured in the listings. For instance, the BASIC variant used in the 8-bit Commodore computers requires the use of various Shift, Commodore key and Ctrl key combinations to produce special screen control characters. These appear in the program listings as inverted graphics symbols, and it is not always obvious from the symbol how you should type it in.
To remedy this, the magazine soon started converting special characters into more explicit key-sequence mnemonics, to make it easier to type them in correctly. They also added checksums on each line.
There was a separate, small, type-in utility program which would help with the checksums. Once loaded and run, it would sit in the background, monitor the user’s keystrokes and calculate a checksum value and display it in the corner of the screen each time you typed in a new BASIC line and pressed Enter. This made it easy to check that you have, in fact, typed in each line exactly as intended.
In many homes, it was the responsibility of a dutiful adult (mommy or daddy) to read aloud the program code from the magazine which their offspring would then type in as dictated.
Later on, the program listings started turning increasingly into BASIC loaders for machine-language code. The program would start with a small routine which would read raw byte values from DATA statements in a loop and copy them into a suitable memory area, then start executing that data as machine language code. The rest of the code to be typed in would have been just endless DATA statements with comma-separated decimal numbers, or a bit later, gobbledygok strings resembling Base64 encoding. This allowed distributing more capable programs (since machine language allowed using the capabilities of the computer to the fullest) but those endless DATA statements were no longer fun to type in or look at, as you could not really study what was going on by looking at the program listing.
All in all, it was a very inefficient and cumbersome method of distributing software. Yet, getting your hands on a new issue fresh off the press and seeing what kind of new programs they had published this time was exciting, as was the idea of being part of this larger community of hobbyists where ordinary people could have their self-written computer programs published and distributed to the masses in this rather public way — on the pages of a widely-circulated magazine.
Magazines were not the only source of type-in programs. The user guides provided with the computer usually came with a BASIC programming manual that had small type-in sample programs demonstrating various features.
There were also many programming books catering for the hobbyist programmer / microcomputer / home computer market, also featuring type-in programs.
(Answer partially based on my similar answer first published on Quora.)