The purpose of the different waqf وقف (pausing) signs is to smoothen the recitation. As the reader or reciter is reciting Allahs words, he is asked to recite them in the best manner (73:4)! Beside this the purpose of waqf signs is also to clearify the meaning, by building clear sentences. So anywhere were scholars have chosen a so called waqf lazim (necessary pause) the meaning is complete, anywhere where there are options, the meaning is incomplete or has a relation either to what comes next or what was before. Even if I'm not 100% familiar with the waqf's used in most moshafs which are wide spread due to the prevalence of the qira'a of Hafs (Difference of waqf in Qiraat Hafs between waqf الوقف in usual Moshaf and turkish recitation) as I've grown up with the simple wafs signs of imam al-Hibti محمد بن أبي جمعة الهبطي, as you may see in the answer of What are the different punctuation in Quran?, I'll be glad to elaborate and explain for each.
But note that these marks or signs are not part of the rasm of the qur'an and even were unknown to earlier generations as they are based on the ijtihad of scholars whom dealt with waqf and dabt ضبط or ibtidaa' ابتداء (pausing and accuracy? or starting -after a pause-) and tajweed most of the signs used in moshafs today have been invented, defined and fixed by scholars (AFAIK) untill the 10th hijri century.
Therefore there are two statements often to be found in the appendix of a moshaf copy:
The sunnah of the prophet () was to stop/pause at the end of a verse (see for example in sunan abi Dawod).
ليس في القرآن وقف وجب or ليس في القرآن وقف لازم
which means there is no obligatory (neither Allah nor his prophet ordered us to do so) waqf in the qur'an.
As anything else then the content of the Qur'an is a matter of ijtihad, we don't have clear statements defining the length of most verses and their amount (see for example my answer on How many ayaths are there in Al-Quran?).
So most scholars of qira'a chose to pause at the end of a verse, what they have chosen as the end comes from how they've received the recitation via oral transmission and by ijtihad using their knowledge of the Arabic language.