This topic is in response to a few private questions during our session on 24th December 7am IST.
Source: Python Datacamp Tutorial on designing solution for Kaggle Titanic Competition
During Data Cleaning, the titanic dataset is an example where you may not want to impute all the values for an attribute.
The Tutorial link will take you through coming to a base solution for the Kaggle competition. The Titanic competition has no prizes and is just for beginners that are new to Kaggle. The Datacamp tutorial goes through fine-tuning models as well but you need to tune it further after the tutorial to get to a decent solution.