SQL Server maintenance plans
If you need to shrink your log file often, it means that the size it has after a shrink is not sufficient for your everyday activity, so it grows again and again. 

This means that you do unnecessary work when shrink it, and, that is worse, every time your log needs to expand, it wastes time zeroing out every new piece of file it adds (and your users WAIT for the completion of this zeroing out).

You should stop this double waste of time and eliminate log shrinking from your maintenance plan. If you are not satisfied with the size of your log, shrink it once and then make your log backups more frequently.