I hardly dare to comment when my teacher, Madhav Deshpande, is on this list as well, and what little I know I know from him, but.... I recall very well learning that external sandhi is, according to the grammarians, always optional.
Because
One
Can
Always
Speak
Like 
This
If 
One 
Wants
To.
In other words, the use of sandhi is a convention, so the question might be slightly rephrased as: what are the conventions of the poets, and of the scribes. No?
(Perhaps, as is quite likely, of course, this was implied in the question, and I should have kept my ideas to myself.
In
Which
Case,
Sorry ;)

Jonathan

On Thu, Jul 28, 2016 at 4:26 PM, Valerie Roebuck <vjroebuck@btinternet.com> wrote:
Correction: I meant ‘at the end of one line’.

> I’ve just had a quick look at an edition of the Saundaryalaharī, in Śikhariṇī (17 syllables to a line), and sandhi is broken only between half verses and whole verses. For example, there's a ś  at the end of one half-line followed by a c at the beginning of the next.

Valerie J Roebuck
Manchester, UK

> On 28 Jul 2016, at 15:07, Harry Spier <hspier.muktabodha@gmail.com> wrote:
>
> Dear list members,
>
> In the longer sanskrit meters (Vasantatilaka for examplbe 14 syllables to a line) is Sandhi broken after each line or only after the half verse and end of verse.
>
> Thank you,
> Vasishtha
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--
J. Silk
Leiden University
Leiden University Institute for Area Studies, LIAS
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