If I wanted to buy $1,400 of bitcoin every week, should I buy $200 a day or should I buy the $1,400 every week?
It's totally up to you. You are the one to decide. If you are following dollar cost averaging method to invest in BTC, pick any time frame and follow that. It can be a daily $200 or weekly $1400. Frequency is something you should set first, it depends on your time, fund availability etc.