I've noticed that weekly time frames 'explain' an number of changes in directions of markets - especially forex markets. My thoughts on this follow.
Weekly time frames represent big moves that are probably related to issues or big economic issues affecting countries. I speculate that much of these moves involve decisions. These sort of players are the 'big boys' with the big financial muscle.
In general levels (oblique and horizontal) on the weeklies, channels and so on, tend to hold more power than on lower time frames. Even breaks out of these key levels can be temporary.
I don't think any average trader would be trading on a weekly time frame, as a position could take months or even years to unfold and bear fruit. Naturally most traders would be trading well below daily time frames.
What might look like a good position for entry on a 4H time frame could well unpleasantly surprise a trader (namely me - from experience) - and then when I look to the weekly the 'answer' is there.
I normally trade between 1H and 4H time frames. Regularly now I look at the weekly and monthly time frames to see what the 'big boys' are doing.
On some occasions - after careful assessment - I would 'take a loss' (i.e. a stop-loss) near a potential weekly reversal point. On other occasions where did not do so, I realised that the market did reverse.
It is possible to make a tight entry position on a potential weekly time frame, then follow a trend on say the 1H or 4H time frames. This could mean getting ahead of the crowd and getting out earlier with some nice profits.
Of the utmost importance is taking that reasonable and acceptable loss (the stop-loss). I never chase on a weekly time frame.