Yes, that's correct. You can use any seed you want as long as it is an integer. We use seeds so we get the same "random" numbers each time. In homework assignments, a professor might ask to use a seed so the homework is all the same but that's the only time it would really matter to use the seed in an example or template script. Otherwise, when you begin a script, you can specify whatever seed you want. 123 isn't special.
Seeds are useful in production in my work when I'm drawing a sample that we will then mail survey invitations to. If someone re-runs the script, we get the same sample. We set it at the beginning and never change it because we don't want to get a different sample.