I use Alt + Shift to change the language. It is so normal and I have worked with that for a long time. But some days some thing have happen for me. That is Alt + Shift not work all times. For example I can use it on libreOffice to change the language and also on browses. But on some application it does not work. I do not know why.
For example on Taskque software, when I want to add my own task and change the language, Alt+Shift doesn't work.