RE:How long should I waitOthers here can provide a much more detailed explanation but here are a few things to keep in mind.
You are essentially comparing apples and oranges in terms of your underlying investment premise. Just because two companies are clumped into the same industry designation doesn't mean that they are identical. Differences lead to differences in how the big investors value a company and in turn this affects SP peformance.
Here is a brief general (somewhat simplified) summary of some of the differences between SU and CNQ as an example of this...
Produce oil..........both
Produce NG........CNQ
Refineries........... SU
Gas Stations........SU
When you look at it from this perspective it is not difficult to see that they would react differently to economic events.
So for example if we take EVs. SU will be more impacted since it owns gas stations and owns refineries that produce transportation fuels than say would be the case for CNQ. Plus CNQ produces natural gas which softens any impact of oil reduction oil usage in the transportation sector on its earnings.
There is a lot more to this but I suspect you get the idea. Others here could provide a more granular explanation.