They can change, not super common and to my knowledge no real pattern on when / why they change. Just Jagex being Jagex.
Also here is a link to the DreamBot educational Discord -> https://discord.gg/wvZaH3W
You will need to do some trail and error / experimentation to figure out what works best for you and your setup. There is no "Just do X and you'll print money" If it were that easy everyone would be doing it lol.