Here's how you can pursue continuing education in 3D Modeling with limited time.

Of course online courses are great to learn any tool from scratch. But what is better than that is to go with live online classes as you will get live feedback as well. Feedback plays a vital role in the process of learning. If feedback is not correct or up to the mark, you may learn things in the wrong manner (there are chances).

Best way to absorb information by learning is to also practice doing what you are learning. This is because by learning passively your focus may be all over the place and so you lose potentially valuable information and secondly by practicing what you learn, you are more invested in the work and when you also become more interested, you will start learning properly! Some examples include live mentorships, working on revenue share projects, or self-initiatively watching online tutorials and following steps taught in courses. As for subject to learn, this is up to you to decide which topic interests you and how you see yourself in the near future.

According to me, tutorials are great to upgrade your skills only and only if you have good knowledge about software. If you have prior knowledge you can focus on the process rather than tools (as you are aware about it). and if you dont know any specific tools you can easily learn the usecase of that particular tool and its very easy to grasp it.

There is a limited time a human brain can actively take in information without losing absorption efficiency, so you should schedule time to learn and try to be disciplined about it. Be patient and positive, remind yourself why you wish to learn what you are learning and let that motivational drive push you forward. Practice makes perfect, results will not come to you over night so be prepared to spend longer amounts of time but the results are worth it and if you gradually learn, practice and don't push yourself too hard, you will grow exponentially!

If you feel overwhelmed with ambitions, reduce the project complexity and scope to manageable ones. You will get further by working on smaller, easier projects that inspire you than dwelling on harder, bigger ones that place you in a place of despair and make you feel like you want to quit. That's not to say you aren't capable of doing greater, bigger, more complex projects, it just means you need to switch your gears more carefully and slow down so that your "engine" doesn't overheat and die, but with some time eventually you will gain stamina to tackle the latter as well.

With limited time consider joining low-commitment/low stakes community projects that might be outside your niche to practice your skills in modeling. For instance, game modding communities are always in need of talent and provide avenues to try new workflows.