Straightforward case - all the required, strong proofs, no/not many red flags (like for example: big age gap, quick marriage without any visits), no criminal past or problems with immigration (for example, a refugee who was rejected and had to be deported). Also, if you were not married before/have been in a common-law relationship, that makes it more straightforward. If the sponsor was not sponsored him/herself in the past, then divorced to marry and sponsor another person, that's better. If the sponsor is living outside Canada, there would be an additional step to prove he/she would definitely come back to live there with the applicant. All of those things can delay an application more or less, and require it to have stronger evidence.