It may seem lazy to some, but some may prefer a singular rain free location. It may be a case of practicality if Candidates want to petition from home on a rainy day (paper forms), and many to come in that period in Vancouver, BC. Also they may not want to be all over the place if someone is going to seek them out. Finally, it shows a true dedication by the voter to choice on the ballot and gives them a right to complain about the lack of it, also if they win and dodge you at the constituency office you might know places they will be.