Are girdles generally added for big rpm or HP or torque

Had a 414 stroker that I ran a couple years, it made 515Hp, when I took it to the machinist he showed me the signs. Number 2 and 4. Pretty bad so he said. It ended up being a "shot" block in the end, so we didn't have to address the issue.

Current engine ran last year 2100 miles. It never leaves the garage without a couple passes. Pretty hard use. Had to tear it apart to ease my own mind, but the maincaps look new as well as the block mating surfaces. This is a 4 speed car with 430 gears and pretty sticky tires. No walk at all.

I don't consider wasting money on anything in my motor that MIGHT help. It can't hurt.
IM, in relations to Rumble's question.... did your machinist explain what is causing the cap walk?

didn`t read all these posts, but some of u guys are missing the point. A girdle will strengthen a big block/r/b, probly more than any other block made , just because of its weak design. The girdles purpose is to stop the mainstuds from whipping around causing cap walk that breaks the block between the main and cam bores, in a ''higher'' h.p. hi RPM situation. More for engines that are run all the time in upper RPM . There are a lot of tricks to be used, all of them together should make a 440 , which is the worst , more dependable and last longer. In my case I use one because I don't want any future troubles, not that I run at higher rpm a whole lot.
Alum. main caps w/ studs , main studs by them selves , girdles , cryo treatment , block filling , line honing/boring , all will help a r/b .
A mega type block would solve a lot of this "if," u can afford one.
I`ve always had to buy parts a little at a time , never could afford to come up w/ a mega , or alum. aftermarket block all at once .
Some blocks will break in that area faster than others . I know a guy that even broke mega blocks between the main and cam bores " ,
dragcar-----------he eventually backed the linkage off to run consistant 9: 60`s, with alum. caps and studs .
I built a really hot 406sbc, that I had machined for 4 bolt mains , it still cap walked on every cap------
Same question to FB... Is there an explanation of what is making the caps/studs to whip around? Is this just crank flexing working through the bearings, or some resonance, or ???? This article for Ford mentions 'harmonics', which indicates resonant problems.
D.S.S. Racing - Main Support System And Pro-Tray Windage Control<meta name="description" content="D.S.S. Racing's Main Support System Dampens Harmful Harmonics That Cause Cap Walk And Can Crack Engine Blocks. The Main Support System Is Affordable And Easily Installed. D.S.S. Also Offers Increased HP With The Pro-Tray Windage Control.">

And yes, the girdles have the strength to control this direction of movement. This sounds like a good explanation. Many thanks!