I am planning to apply to universities abroad in the next two terms, but I haven't finalized which institutions I will be applying to yet. I understand that recommendation letters are a key part of the application process, and I have already approached a few professors about writing them for me.
One professor mentioned that, typically, students send them a link when the application is ready, and they fill out the recommendation online. My concern is that if I wait until I finalize my university choices, some professors might not be available to submit their letters due to scheduling conflicts or other reasons.
Given this, would it be advisable to ask my professors to write physical recommendation letters now, which I can later submit when the application process begins? Or should I wait and rely on the online submission system when the time comes? Also, are physical recommendation letters accepted by most universities, or is an online submission system required for all?