The process of having to describe your study in detail, in a logical sequence of written words, will inevitably highlight where more thought is needed, and it may lead to new insight into connections, implications, rationale, relevance, and may lead to new ideas for further research.
Barras (196) suggests that you ‘think of your report as part of your investigation, not as a duty to be undertaken when your work is otherwise complete’, and this Study Guide suggests that: writing is an integral part of the research process.
You will need to check which style of reporting is preferred in your field.
For example a scientific dissertation would probably have very clear separation between the results and the discussion of those results; whereas a social science dissertation might have an overall chapter called Findings, bringing the results and their discussion together.
Any imbalance in space devoted to different sections of content will become apparent.
This is a useful check on whether amalgamation of sections, or creation of further sections or sub-sections is needed.
The Abstract is an important element of the thesis, and will become a document in its own right if the thesis is registered within any database.
The examiners will therefore assess your Abstract both as part of your thesis, and as a potentially independent document.
It can be best to write the Abstract last, once you are sure what exactly you are summarising.
Alternatively it can be useful to write the abstract earlier on, as an aid to identifying the crucial main thread of your research, its purpose, and its findings, which could then guide the structure of the dissertation.