Time can be a consideration. The Insight book describes all kinds of sins (very large and quite small). It may take a different amount of time to address and solve the various problems we are faced with. A small sin might be an individual act that is quickly recognized and immediately dealt with. Other sins might involve multiple parties and require months or even years to unravel and fix.
In the case of the jailer and his family at Philippi, the entire repentance, conversion and acceptance of Truth took one night. Manasseh took years.
The 2013 Watchtower quoted below mentions it is an "on-going process". Sinful humans continue to sin.
*** w13 3/15 p. 16 par. 14 Having âCome to Know GodââWhat Now? ***
14 Our initially becoming a Christian depended on repentance and on turning around, or turning away from our sins. Repentance, however, is an ongoing process. As imperfect humans, we still have sin lurking within us like a coiled snake ready to strike. (Rom. 3:9, 10; 6:12-14)
*** it-2 âRepentanceâ par. 10 ***
What true repentance requires. Repentance involves both mind and heart. The wrongness of the course or act must be recognized, and this requires an acknowledgment that Godâs standards and will are righteous.
The person must see that he has sinned against God. (Ps 51:3, 4; Jer 3:25) Even wrongs committed in ignorance or by mistake are to be recognized as making one guilty before the Sovereign Ruler, Jehovah God.âCompare Le 5:17-19; Ps 51:5, 6; 119:67; 1Ti 1:13-16.
Regret, remorse, and tears, then, are not a certain measure of genuine repentance; the heart motive is determinative.