The imams of shias played a strategy which is summed up in this Shia narration.
It is reported from Aa‟imma, who said “We have put some divisions among you in order to save yours and ours lives, because if you were seen standing on a single platform then your identification might be easy; and it would have resulted in your demise.” Therefore, these shrewd individuals, who are godly trained, gave the true answer of a problem to some trusted individuals and the rest are provided with a disguised answer. This had made the less scholarly little baffled, while those who were accustomed with the diction of the Imams, knew what the real reply was and what was under the influence of Taqiyya?
Essence of Shia Faith by Sheikh Saduq, Explanations of the Text by Ayatullah Hussain Najafi, English Translation by Safi Hassan, p. 557
Now read what Sheikh Tusi says in his book 'Tahtheeb ul Ahkam'
And among the Hadiths (narrated) by our companions (Shia scholars/companions of the Imams) are so many disparities, contrast, contravening and contradictions that you will not find a single report that we agree upon which doesn’t have another that contradicts it, and not a single Hadith is safe from another which denies it. These (contradictions) are to such an extent that our opponents (the Muslims/Ahl Al-Sunnah) have used it as the biggest accusation/attack against our school and as a proof for the falsehood of our creed.
(Until he said): ‘… and this is why a number (of Shias) have left the true creed and amongst them are the likes of Abu Al-Hassan Al-Harouni Al-Alawi, who used to be on the true creed, upon the creed of Imamah (Imamate), but he turned away from it when confusion overtook him due to the issue of the contradicting Hadiths. So he left the school (of Shiism) and attached himself to another (school), as he could not grasp the different understanding (of our text) and this is an indication that the did not embraced it (Shiism) without insight, rather based on Taqleed.
Tahtheeb Al-Ahkam, Vol. 1, p. 8, by Sheikh Tusi
In order to protect their followers, the Shia imams are attributed to have said that they created the division to protect their followers. But from Sheikh Tusi, the great scholar of Shias, we come to know that this strategy failed miserably. This only led their followers astray, so much that some of them left this creed due to confusion.
Did the Imam's strategy succeeded? Of course no. His strategy was doomed to fail. It was like during a battle, he distributed uniforms of different armies in his soldiers in order to protect them. But this made his soldiers confused, and they started killing one another. One more reason to prolong the ghayba of the twelfth imam.