Short answer: Yes.

Of the HYPSM schools, all are single choice early action except MIT. As my son applied early to Princeton, he could not apply early to any other private school. He did however apply early to Michigan and was accepted there. After being deferred from Princeton, he applied to many schools as part of the regular decision process. The application to Yale was submitted near the end of December.

As you said, most likely letters are for athletics. They are given almost a year before the student joins college (like say September 2019 for a student joining college September 2020). The student-athlete then applies early action fully expecting to be admitted.

Most and perhaps all Ivys also send out a smaller number of non-athlete likely letters as part of the regular decision process. Depending upon the college, these get sent out anywhere from near the end of January to early March. The goal is to get the recipients to think highly about this college before hearing about all other college decisions later in March.

As we recently learned, Yale generates about 100 likely letters specifically targeting STEM kids, and follows that up with a Yale Engineering and Science Weekend (YES-W) where they bring in these kids and try to get them to fall in love with Yale. Apparently STEM is where Yale wants to strengthen its student body.

In contrast, I have heard that Stanford sends its likely letters to humanities kids, as it has plenty of strong STEM kids already. Harvard sends its likely letters out in mid-February. It doesn't target any specific set of majors for its likely letters, but sends them out to whoever they think will best strengthen its student body.