Always opt for bracing when possible. Remove all possible motion from every lift other than the joint/s working to engage the targeted muscle. In this case, brace hard against the rack and totally still try e rest if your body. Also, I realize I’ve got some trap involvement in this lift video. You can see my delt squeezing into my neck to some degree at the top. That’s because I had a lot of shoulder content to film this day and was getting seriously fatigued. Try to avoid that and just focus on the deltoid flexing the arm as high as it goes until before the trap engages.

Honestly, whenever possible, it’s always a goid idea to get a vid if your top working set/s just to watch for these kinds of corrections that could be made to further perfecting your form and optimizing your effort.