There is good and bad to the cliché advice of “studying magic” for the “sake of development” and “learn as much as you can”, below are what I think the pros and cons to learning all you can.
The pro – learning sleights and practicing ones you may or may not use will come in handy. It will allow you to exercise your hands and be more proficient a magician. There have been many times that I have had to think quickly to recover with “sleight B” and still achieve an effect when “sleight A” has gone amiss. Like when you perform a pass and bring an accidently brought it to the bottom or second to the top…moves you may not have used would allow you an out. It may help your creative process too, as you will know more solutions to a given problem - knowing 5 ways to reverse a card, could come in handy when working on something, more so than just knowing one. I think Draven sort of touched on this when he said, “You will never know what you can take from these slights and apply to other areas of your career”, which is true, but because he didn’t really explain how, and someone asking the kind of question you are,I figured you may not be able to read between the lines to understand the importance of the statement. (not calling you stupid, but Draven's post took me a couple reads and I am still not sure I grasp the ambiguity, yet concise, nature of his statement - ha - I bet you missed me Draven.) On a similar note, I don't nececssarily agree with Draven's last statement that "While learning to perfection may be a bit unecessary, Technical knoweldge and practical working experience should be a requirement." But in hoping to agree, that he meant that you should strive for perfection of method, (that being that a keen observer could not detect method) that you should also focus on having entertainment value in your magic. That perfection is a goal, but one that you will strive for, for the rest of your time in magic - as even the best performers of any given sleight still work constantly to improve it.
Anyhow - it reminds me of a line in Sherlock Holmes - Knowledge is it's own reward - as learning more will help you progress. That being said...
The con – Learning moves for the sake of development, would be like thinking you had to memorize all your times tables in math to be able to do math. Some sleights you won’t want to learn – not because they are a waste of time, but because they are not efficient. This is where you have to be…here it comes…A CRITICAL THINKER…you have to think! For example, the “ego change” has been a popular move in the last year, but is this the best change if your audience is seated? How about standing? Surrounded? So, you should be thinking about your venue, and how the method affects the effect. Can I do the ego change? Yep. Do I ever use it? Not really. I learnt it for me, to experiment with it, but there are many things I haven’t learnt and don’t intend to as the effort to learn and master the sleight is far greater than the impact it will have - a good example for me is Ray Kosby's Raise Rise. The move is not easy, and the amount of time it would take for me to make it look natural and moveless, would be great, and I don't find it that versatile a move. I use other methods to create the same effect, that are more efficient and versatile.
I would rather see you be amazing and 20 sleights, then mediocre with 50.
The way I learnt sleights was of necessity. I would read or see an effect I like, then learn and master what I had to be good at to perform it. As I grew in magic, I would learn the extras as weapons to add to my arsenal, if needed. Also, learning new techniques challenges you – and since magic is a large part practice – this helps prevent you from getting bored.
There are many talented magicians that think to be considered good at cards you should learn these things, then variations of these 7 things.
Control to top and bottom
Double Lift
Top Change
Colour Change
False Shuffle
Palm top and bottom
Force
I would add to that list a few false counts, like the Elmsley...at least then you could do many store bought packet effects, if that is your thing.
If you can do these things well, and 2-3 variations of each well, then you are in the top 10% of all card handlers.
Hope it wasn't a waste of my time writing this - and it helps you with your magic.
