***** NOT A TEACHER *****
(1) In/on? A very difficult matter.
(2) There are some general rules that you can learn in books and on the Web.
(3) The best way is to read - read - read.
(4) If it's a big island, we say IN; if it's a small island, we use ON.
(a) But what is "big" and what is "small"???
(b) Your idea about using IN with the names of countries seems very helpful.
(i) But when I was young, people used to refer to events ON Taiwan (an island). Today, EVERYbody says IN.
(ii) Maybe twenty years ago, people spoke about events ON the West Bank (maybe because of the word "bank"). Today everybody says IN.
(5) I think that many (most?) people now refer to events IN the "mainland" while others prefer ON the mainland.
(6) All of the examples you gave us seem to be correct. I have a question only about "I live in a ranch." I prefer ON, but I could be wrong.
(7) Thanks for your interesting question. Let's see what other contributors say.
(8) Remember to read - read - read. And keep a list of what words are used with "on" and what words are used with "in." (A little problem: sometimes American and British English do not agree on which preposition to use!!!)
Have a nice day!
Student or Learner