Here's one advice in a recent article:
"... if the stock has hit rock bottom, but is set to rise aggressively, then it is better to just invest a lump sum to take advantage of the rise."
Oh right, that is so obvious. Surely.
How does one know that the stock has hit rock bottom? Only hindsight can tell.
How do you know that it is set to rise? That requires clairvoyance. God mode needed.
Conclusion: Got say like never say. Smart sounding piece of utterly useless advice.