“Rivers are easiest to cross at the source.”
–Publilius Syrus

Before starting a journey it’s a good idea to chart a course. Starting with a plan allows for a greater chance of success and a lesser chance for failure. If you begin with the end in mind and create a plan, then you’ll have a road map and a process of how to achieve the success you want.
The process of creating a plan enables you to break down the distant goal on the horizon into smaller, easier to conceptualize and achievable parts. Hopefully a plan will emerge that has steps that can be accomplished incrementally. If someone has gone before you, and often there is a pioneer that will have blazed a trail for you, you can be aware of some of the obstacles that you might need to overcome. Knowing what lies potentially in front of you will help you to prepare better and surmount obstacles as they arise.
When starting a musical journey, the first important work is developing habits that will serve you for as long as you choose your journey to last. This is not always self-evident nor the most expedient path to learn to play an instrument. There are many short-cuts at your disposal that can help you to play well enough to survive as a working musician but may leave you with one or more habits that can eventually become obstacles to your development. Also, as Syrus implies, the river gets more difficult to cross the further we travel from its source.
Think of any basic technique you were taught at the very beginning, for example, alternate finger plucking on bass. At the start you didn’t have any notion of a correct way to do it. You may have started with just your index finger and then added your middle finger occasionally when there was phrase too fast to play with just your index finger. As your proficiency increased, you may have found that your plucking technique was a limiting factor when it came to playing faster and more rhythmically challenging parts. After years of playing, you may find that you need to retrain both your mind and fingers to alternate correctly. Had you crossed the river at the source in the beginning, you might have lagged at the outset, but could be further ahead now.
Trust the process. If a teacher, mentor, or instructional book suggests a process for building technique and knowledge, and you think it’s valid, then trust it and follow it. It doesn’t guarantee success, but it has worked for others. Each of us is different. What may take you one week may take another person much more time. Conversely, what you find difficult, others may find easy. We are each physiologically and psychologically unique. That means that your path to get somewhere may be slightly different at some or many points during your journey. When you put your trust in the process, you can concentrate on a very small segment of the path and work on perfecting it knowing that it is a necessary step. Always looking at how much more remains in front of you or how much faster others may be traveling is usually counterproductive.
Bottom Line: Small incremental progress builds a wide and solid base.