Learning particular technologies in-depth is waste of time
Not only did I waste time by reading books cover to cover, but I also often choose to read the wrong books. I had mistakenly believed that learning a particular technology inside-out would be a good way to advance my career.
I spent too much time reading books about very specific technologies, While it is important to know about the technology you are using, it isn’t important to be an absolute expert in that particular technology. There isn’t much benefit to knowing the exact API call to make when you can just easily look it up when you need it.
Too many technologies that I spent a good amount of time learning about in depth, ended up either dying out or being technologies that I eventually abandoned myself. Most of the knowledge about those specific technologies ended up representing a big waste of time.
I found that it was important to become an expert at whatever programming language that I was using at the time, because expertise in a particular programming language will usually last you a pretty long time; I definitely would have still spent time learning in depth about C# and Python but, I perhaps, spent a little too much time learning all the intricacies of C#, which isn’t benefiting me much now