A couple of years ago I was coaching some music with a friend of mine, a wonderful coach. In the course of the hour, I observed,
“Y’know, I have recently been thinking a lot about the relationship between a hook-up (another term for “support”) and legato, and how....”
“...They are the same thing?”
“Well, sorta. Not exactly the same. But they are reeeally related.... like, Siamese twins related.”
“Like, sharing vital organs related?”
This funny exchange does get at the heart of a truth in the development of skill. There is usually more than one way to skin a cat. And it is very often an attack from the (seemingly) opposite end of the problem.
While it remains true (in my experience) that consistent, sufficient support (“hook-up” is the term I inherited from my teacher) is incredibly helpful to the development and maintenance of steady and even legato, it is not, in the strictest sense, necessary. In fact, there have been a great many singers of non-classical music whose balladeering has demonstrated spectacularly beautiful phrasing, and whose sense of line has allowed them to tackle challenging tessitura in spite of a generally minimal, or only just sufficient, support. In short, as much as support helps and encourages legato, it is just as true that a good sense of legato and phrasing can help to spur on a support that is better than is generally present in the singer.
It is this way with many things. The problem can be dealt with from both ends. Another example: It is true that keeping steadier breath flow will help with keeping an open throat. And yet, trying to maintain a physical sensation of an open throat is one manner of allowing for easier passage of breath. Either way you approach the issue, you benefit.
Finding and developing exercises that cultivate skills from both ends is incredibly helpful and, frankly, usually necessarily. Eg. knowing how and when to “let go” and when to “control”, when to be stronger, when to be gentler - what natural patterns to follow, what habitual patterns to break - how to learn to have a legato feeling underneath a staccato or melismatic passage, and how to develop clear diction that doesn’t break legato, and may even be projected yet better by that same legato - understanding that soft singing is often helped considerably by an understanding of better, fuller phonation, and learning to sing loud is often improved by understanding how to sing softly ...... these dichotomies will necessitate approaching these issues from many different directions, and sometimes what seems like a particular aspect's polar opposite. So, allow the pendulum to swing far to both sides sometimes in your practice. At some point, you will begin to sense the healthy, balanced middle.