It is necessary in singing, as in life, to have appropriate boundaries. Not to have them or be able to understand their usefulness is a mistake.
Even if you sing well and have solid vocal technique/function the only way to know what your voice wants to do happily is to work on repertoire. You can’t really determine how your voice will feel best doing only exercises. You have to read through and then thoroughly work repertoire of various eras, composers and styles in order to find out what your voice can and cannot do easily.
Yes, you can choose to make your voice and body sing in an unnatural manner through lots of hard work on both sound and breathing. Yes, you could manage to sing that way and survive. You may even end up sounding very good and making a great impression, but singing this way will require you to give up everything outside the sound as you have cultivated it. You will sacrifice variability for consistency. If, as an adult, you truly want to make this choice, and are informed about its consequences, you have that right.
If you want to be able to sing with maximum freedom and versatility, however, you need to find out what happens when songs fully reside in your throat. If you work on a piece that exhausts your voice even though you are technically secure, that piece is a wrong choice. If you want to do contrasting pieces and styles, and you find that one style truly interferes with the other, then one of those styles has to be adjusted vocally or you can’t sing them both. If you want a chesty penetrating high belt and a soft floaty heady high, alternately, I will tell you now — that isn’t really possible. It’s the old saw, “You can have anything you want, you just can’t have everything you want.”
Too much weight in the middle voice will (yes, WILL) pull you out of your top tones no matter how much breath support you provide and how much you work on “forward resonance”. It might feel good and sound fine, but it will not work up high. It will not. If you want to have easy high notes, the middle has to be calibrated such that it’s heady enough to stay connected to the high range without effort. You cannot make that work some other way. While you are young, however, you can probably get away with trying. After that, age will start to calcify your thyroid cartilage and you won’t be so lucky.
Will you read about this somewhere? I don’t think so. Am I correct? You will have to take my word or wait and see for yourself. If you are going to be a master of moving from one style to another you have to calibrate the entire machine to be able to do that easily and keep doing that all the time. If you are going to choose to be a high belter or a spinto soprano, you will have to specialize in that and not try to be a star at something very different.
Remember, you need to understand function measured against repertoire. In the end, your throat will tell you how far it can go and still return to the same starting place. It will tell you what it can do to vary things and still have the capacity for them to remain the same when you return to home base, vocally speaking. If you let your throat establish appropriate boundaries and choices are made based on how your throat/voice works in repertoire, you will have a safety net that allows you to sing anything (not everything) you want.