Honestly, the only thing that method is good for is getting caches quicker.
There is a legendary timer, but it doesn't do anything until well after you've probably had a legendary anyway (several hours), and afaik doesn't work on caches.
Even if it did work on caches as soon as you get a legendary that isn't RORG you'd have to stop opening them, go play for several more hours without a legendary then open again until you get a legendary etc. Just opening 30 caches at once (if the timer did actually work on caches, and you'd actually played long enough without a legendary to trigger it) would just increase your chance to get a legendary until you got one, then it would reset and do nothing for the other 25 caches or so.
It IS the best way to get an RORG, but it's not because of the legendary timer, it's because not destroying/opening stuff, killing the minimum amount of monsters is the most efficient way to get caches.
Anyone that says stuff like "I did this and got one after 2 caches" got one because RNG is RNG. Getting one after few caches isn't exactly uncommon, nor is not getting one after 100.