Gathering should not be in haste.  This has do do with counting the cost of being a disciple.  He who is not prepared to sacrifice all, or is not currently sacrificing all, or he that looks back, cannot enter in.

"For ye shall not go out with haste nor go by flight; for the Lord will go before you, and the God of Israel shall be your rearward." (2 Nephi 15:19)

"Wo unto them that draw iniquity with cords of vanity, and sin as it were with a cart rope; That say: Let him make speed, hasten his work, that we may see it; and let the counsel of the Holy One of Israel draw nigh and come, that we may know it. Wo unto them that call evil good, and good evil, that put darkness for light, and light for darkness, that put bitter for sweet, and sweet for bitter!  Wo unto the wise in their own eyes and prudent in their own sight!  Wo unto the mighty to drink wine, and men of strength to mingle strong drink; Who justify the wicked for reward, and take away the righteousness of the righteous from him!" (2 Nephi 15:18-23, Isaiah 5:18-23)

"For ye shall not go out with haste nor go by flight; for the Lord will go before you, and the God of Israel shall be your rearward." (3 Nephi 20:42)

"And let the work of the gathering be not in haste, nor by flight; but let it be done as it shall be counseled by the elders of the church at the conferences, according to the knowledge which they receive from time to time." (D&C 58:56)

"And let the residue take their journey from St. Louis, two by two, and preach the word, not in haste, among the congregations of the wicked, until they return to the churches from whence they came....And after thou hast come up unto the land of Zion, and hast proclaimed my word, thou shalt speedily return, proclaiming my word among the congregations of the wicked, not in haste, neither in wrath nor with strife." (D&C 60:8-14)

"And now, behold, this is the will of the Lord your God concerning his saints, that they should assemble themselves together unto the land of Zion, not in haste, lest there should be confusion, which bringeth pestilence." (D&C 63:24)

"Therefore, a commandment I give unto all the churches, that they shall continue to gather together unto the places which I have appointed.  Nevertheless, as I have said unto you in a former commandment, let not your gathering be in haste, nor by flight; but let all things be prepared before you....All the land which can be purchased in Jackson county, and the counties round about, and leave the residue in mine hand. Now, verily I say unto you, let all the churches gather together all their moneys; let these things be done in their time, but not in haste; and observe to have all things prepared before you." (D&C 101:71-72)

"But verily, thus saith the Lord, let not your flight be in haste, but let all things be prepared before you; and he that goeth, let him not look back lest sudden destruction shall come upon him." (D&C 133:15)