Whether to or not depends on the desired result. I have on occasion, and not in others. Typically, I'll use frost for more downtempo or ballad performances (singing) and a harder edge for more uptempo stuff but even that's not a hard and fast rule.
There's no hard and fast rule for hard or soft edges
On our spot, there is a focus knob, so if I ant the edges blurred, I just move that al ittle bit. Usually, I try to keep it hard. But, sometimes I'll use the spot like another bright light to add another color if I really need one--case in point, today was Youth Sunday, and for a drama, instead of going up in the lift and changing out a few lamps to a different gel, partly because I didn't have the time and partly because I didn't have the gels, I just grabbed our followspot from next door and slipped a red gel in that, and had them dim the truss lights (like, all the stage lights....pars, leko's and fresnels) a little bit. Worked well.
Once upon a time I did slip in a diffusor to see what it would do, but it turned out that we have 8 and 6 inch frames for our Par 64's, and fresnels/leko's. The frame for the spot must be more like 5 or 4 inches. I didn't have a frame to fit, and no gel either, and I wasn't willign to sacrifice my one single diffusion gel.
Personally i feel that the look has its place in theatre as does everyting else in moderation. As an operator, it tends to look pretty good while using a telerad but for that show that doesn't travel w/ rads your light gets washed out pretty quickly @ 200 feet. I had a show like that the other day where i had to use a diffused super trooper 2k without a telerad, lets just say i'm glad the spotlight blended in.
Frost is a tool, that can be used in a follow spot as needed, just like a regular static stage light, and/or in an ML.
I tend to use hard edges for more 'theatrical" events - R&R, varietly acts, etc... where as dance companies want it for ballet, etc... Opera companies can make extensive use of spots - the Metropolitan Opera has 7 Lycian xenons, as example. Mostly used as solo'ist specials, usually in a head shot, half intensity, light lavender and a frost. Mostly to highlight the faces of the principle singers, while not washing out the entire stage with fron light, thus preserving the composition and mood of the scene.
wow. 7 lycians. even more of a reason why my dream in life is to work at the Met.
yea, like everyone else, frost has its time and place. ill sometimes use it in my designs if im just trying to highlight a little bit, but normaly hard edges seem to work better for spots. just my personal preferance though.
Interesting. My personal preference for anything besides a talent show is a soft edge. I like the extra light, but I don't like seeing the sides of the beam. I like it to blend more into the background. I do this by changing the focus of the spots, not with frost, but its the same effect.
As has been said, its all a matter of personal preference.