I would like to put forward a few suggestions to make this topic area work better for both questioners and experts.
1. Ask Concise Questions
If you can summarize your problem, and extract or highlight RELEVANT code, input, errors oroutput, it is much easiser to answer. If a question contains hundreds of lines of code/data and a request to 'fix this', many experts will not want to spend the time wading through all this. Those that do will probably need to go through several rounds of comments to actually define the real problem.
2. Don't Split the Question
It is annoying to see a question correctly answered, and then have the questioner come back and say thanks, but now I want to do X as well (where X is not always related to the original question). If no more points are offered, it means doing more work for the same reward. It makes it harder to search and retrieve the second part of the question once it becomes a previously asked question. It takes longer to close off the question. It is much better to just start a new question, with perhaps a reference to the first part if needed.
3. Don't Abandon Questions
You can see many questions where experts have spent a lot of time developing several good solutions, but the questioner has dissappereed. Sure they will get auto-graded eventually, but this is still not very satisfying.