There's no absolute rule, since everyone is different; this is just my opinion based on my experience. I gained knowledge of the command line about 3 decades a

There's no absolute rule, since everyone is different; this is just my opinion based on my experience. I gained knowledge of the command line about 3 decades ago. It's been useful for all that time, and I expect it to be useful for at least the next 20 years, too (assuming I'm still around). That's a span of half a century; seems like a good long-term investment. I also learned many different development environments; they were very useful, too, but they had a much shorter half-life. At one time I could read source code by reading the pattern of holes in a punched paper tape; very useful for "mastery" of DEC PDP-8 development, not so useful now. So both command-line and IDE are good things to learn, but in terms of "mastering," it might be good to save that for the command line. I would say definitely learn the IDE, but only enough to get things done with it and to get general knowledge of how IDEs work. Detailed knowledge of every last option, bell, and whistle in one particular IDE may be of limited long-term usefulness.