Android dictation timeout
Speaking Email dictation keeps listening for 10 seconds to allow you to pause for breath, and then asks if you are finished. It gives you the opportunity to say "more" and add more text.
However, this feature relies on the operating system dictation and some versions of Android operating system will not allow silence this long and unfortunately a pause of a couple of seconds will stop the dictation.
Is there a workaround? Basically, you need to speak without pausing. This is a skill you can learn and master with a little practise, although it can certainly be frustrating.