how many days do you guys take until finish a drama?

It depends, when a drama is really good I only watch an episode a day.  Otherwise it's over to soon!

It depends on the drama, if it's really good or not. Sometimes I finish in a week or less, sometimes it takes me to finish in a month

I watch an episode a night, as I’m busy all day and find it difficult to find time. I used to stay up till 6+ am, watching multiple episodes but I cannot do that anymore as it’s really bad for my health. 

If a drama is still airing and released weekly, I can only watch one episode a week. But if some episodes have already aired, I watch one a night. So, it depends how long the drama is, how many episodes and if it is still airing. 

I usually take 1 day and a half. A day and night if I don't do anything else, or watch it while eating. The funny thing is Historical dramas go faster for me since the plot is so thick and I tend to not stop it because I want to know what happens next.

Nowadays,  i finish 16-episode dramas in 3-4 days 

2-3 days, sometimes just 2 if it happens to be over a weekend! Closer to 4 days I'm not super invested, but that doesn't usually happen, since if I'm not invested I'm not going to bother to finish it.

It depends if I'm really into it or if I'm busy.

If I don't have anything that I need to do and I really like what I'm watching, the average time is 1.5 to 3 days. I think the longest would be 4-5 days. The shortest was less than 24 hours (for 16 episodes).