Some of my longest bloomers in the garden require deadheading to extend the show: Salvias, Butterfly Bushes, and Roses to name a few.
Here's a few photos to prove it is worth the effort.
Black and Blue Sage. I trim these rather than deadhead.
Salvia Again, I trim these when the blossoms are spent.
The butterfly bush is still providing food for the butterflies.
Gomphrena in the pot. It's going longer than the petunias. I might
replace the petunias with purple pansies soon and keep the gomphrena until they peter out.
The perennial verbena is still going strong. I hope this survives the winter. I would love to have it again next year. The purple petunias have stopped. What's left of them are in the taller pot in front of the verbena.
Hummingbird moth enjoying the verbena.
Yellow knock out rose. I have read that it's still best to dead head this prolific bloomer. I mistakenly placed three of these in a shady area, but they still make it. Most of the morning they are in shade. They receive Western sun late in the day. A tough spot to be in for a plant.