Personnally, I only prune to shape the plant or keep it inbounds and remove unhealthy or crossing limbs. I also do it at my leisure through winter on nice days, saving the least winter hardy for last. Regarding hardiness, if they can't handle my schedule then they're gone. I'll have 1 final prune in the spring after the canker shows up on some plants.

I suspect if you have that much growth and no canker then it's just a question whether you want short plants.

What you could do is just deadhead them harder this year--take off 1 or 2 or 3' after each round of bloom, as needed to control size--then do your regular pruning next year (if desired). They will be fine.

But Is there any effect to the plant whether I prune this late or not? Any Benefit one way or the other?

It is up to you. No deterrent. They could bloom a week or so later. Or, not. All depends on the weather. If you don't prune them, and if they are hybrid teas, they will get really tall, and you will have blooms way up there. I didn't prune the past two years, and all of the blooms on the hybrid teas were 7'+ in the air. Delightful (not). So, down they will go this year. If I prune as usual, by the beginning of June (I usually prune at the end of March), the plants are full and 4' - 5' tall.

When I prune, I typically have a minimum of 2" of new growth and some plants are totally leafed out by the time I prune. I have some plants with 2" of growth now. No matter, off it goes.

But, if you don't want to, don't. Then, take a look at them after they bloom and proceed as hoovb said. Don't overthink pruning.