I think it was worth making the lecture since your thoughts have changed that much. I wasn't able to make functions in a modular way from the beginning. I spent days thinking about what to separate and how to combine them, and even now, sometimes I think about making a modular structure for a few hours at the shortest and a day or two at the longest. Since it's your first time, it may take a long time to make a modular structure, but it's worth investing time, so don't be too impatient and take your time designing. One thing to keep in mind is that a slapdash implementation is selling the future to buy the present, so don't be tempted to think, "It's hard to think about and it's a waste of time, so should I just slap it and implement it?" Because 'this time' becomes 'next time' and 'in the future'.