many shall run to and fro at the time of the end

Daniel 12:4 says to "Seal the Book until the time of the end." This must signify that the prophecy of Daniel is complete and must be secured and not altered.   It's fulfillment and understanding will be the time of the end, being that time of trouble referenced in Daniel 12:1 (I believe  is the "Great Tribulation" of which Jesus spoke). This does not mean we do not read it and seek to understand it.   But how all the events will play out will be best discerned as they happen. 

Daniel 12:4 says that "many shall run to and fro and knowledge shall increase."    I know that some believe this speaks of our age of modern travel and internet access to information, but I believe this refers to the increase in understanding of prophetic Scriptures in the time of the end, for those who seek it. 

"To and fro" appears several times in the Old Testament (see *below) and just speaks of going back and forth.  

There will be many who will seek out the word of God to understand what's happening, and these will be the "wise" ones of Daniel 12:10:  "Many shall be purified, made white, and refined, but the wicked shall do wickedly; and none of the wicked shall understand, but the wise shall understand."

Compare this understanding with Amos: "12 They shall wander from sea to sea,

And from north to east; They shall run to and fro, seeking the word of the LORD,

But shall not find it." Amos 8:12 

In Amos, we see that the word of God is in view, but in that case, they will seek but not find.  

But in the time of the end, many will go here and there seeking the word of God, and they will understand.

* Then he sent out a raven, which kept going to and fro until the waters had dried up from the earth. Genesis 8:7

 For the eyes of the LORD run to and fro throughout the whole earth, to show Himself strong on behalf of those whose heart is loyal to Him. 2 Chronicles 16:9

And the LORD said to Satan, "From where do you come?"
So Satan answered the LORD and said, "From going to and fro on the earth, and from walking back and forth on it." Job 1:7 2:2

 Will You frighten a leaf driven to and fro?
And will You pursue dry stubble? Job 13:25

He breaks open a shaft away from people;
In places forgotten by feet
They hang far away from men;
They swing to and fro. Job 28:4

And Your plunder shall be gathered
Like the gathering of the caterpillar;
As the running to and fro of locusts,
He shall run upon them. Isaiah 33:4

​"Run to and fro through the streets of Jerusalem;
See now and know;
And seek in her open places
If you can find a man,
If there is anyone who executes judgment,
Who seeks the truth, Jeremiah 5:1

They run to and fro in the city,
They run on the wall;
They climb into the houses,
They enter at the windows like a thief. Joel 2:9

And the man who stood among the myrtle trees answered and said, "These are the ones whom the LORD has sent to walk to and fro throughout the earth." Zechariah 1:10

There are a few more.