I wrote a bit response but realized it may not be what you are looking for. I ended up turning it into a new thread. But here is some information (copy and pasted) from that thread that pertains to your question.
I am not sure if how I study Go would work as well for the 19x19, but it sure works for me on the 9x9. I get asked this question sometimes and so I’ve written a bit about how I personally study Go. It should be noted that I play 9x9 Go 99% of the time.
When I first started Go I experimented with different time settings quite a bit. After a while I noticed that I felt I grew the most from playing Correspondence. But I suspect this came from the fact that I would practice with variations on each move, often trying to predict 20 moves up to game completion.
I learned so much about the game and patterns from this practice. I began using the Conditional Moves feature to regularly as well, trying to see how many moves I could predict from my opponent accurately. I had numerous games going on and this began to feel like a full time job.
So I began playing 10 seconds/move Blitz matches. Slowly I dialed back the Correspondence and focused more and more on the Blitz matches. I ditched the normal Correspondence games and began only playing Fast Correspondence Tournament games (3 Days max time, 12hr move increments). The quality of my opponents greatly improved.
I felt I was able to get more out of my Correspondence with fewer games being played. I did this for about 4 months, striking a 70% Blitz/30% Correspondence ratio for my game playing. Around this time I began to feel strongly that each type of game was teaching me something different.
Correspondence allowed me to learn to improve my reading skills, while Blitz allowed me to develop and exercise my intuition . I learned the vast majority of what I know about Go by treating Correspondence games like a form of solitaire; where my opponents moves gave me new ways to look at the game, identify weaknesses in my Go skill sets, practice and develop better pattern recognition, and my ability to identify and predict what the “next best move” was.
Blitz gave me the ability to put what I was learning to the test against live opponents. There was no time to really sit and deliberate my options. I learned to respond quickly, listening to my gut, and had to rely on what I was learning in my Correspondence games.
What worked slowly became solidified and battle tested, while the stuff that didn’t was eventually abandoned because it never seemed to work in real time matches. Back and forth they went, the knowledge and experience of each strengthening each other, furthering my overall understanding of Go.