Is The United Nations Effective At Peacekeeping?

To what extent is the United Nations effective at peacekeeping?
The United Nations (U.N) as an international organization has its origins in World War II, was coined by United States President Franklin D. Roosevelt when representatives of 26 nations pledged their Governments to continue fighting together against the Axis Powers.
Since then, it has become even more multinational, with over 180 countries around the world registered as member states. The main aims of the UN can be broadly identified via its Millennium development goals (MDGs) :
1. Halving extreme poverty rates
2. Providing primary education in under-developed countries
3. Halting the spread of various diseases- AIDS/HIV/Malaria
4. Promoting of gender equality and women empowerment
Under the leadership of the POLISARIO Front the Saharawi continued their armed struggle for self-determination.
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In April 1991, the United Nations Mission for a Referendum in Western Sahara (Minsuro) was established to implement a peace plan in a Security Council resolution. In September a cease fire was declared. The plan was to conduct a referendum in which Western Saharans would choose between integration with Morocco or independence. After which, the conflict would be resolved.
However, this was not the case, with the mission never fully deploying, as it could not be decided who was eligible to vote. In May 1996 the UN suspended the identification process and recalled most Minurso civilian staff. Military personnel stayed to oversee the truce.
Multiple attempts have since been made for conducting more resolutions, even comprises which consisted of transition periods for decision, but have been rejected by either or both parties. With other worldwide issues taking precedence, the matter has long since been dismissed, most recent actions being the deployment of more troops to keep the
The formation of Republic of South Sudan is the result of over 5 years of peace negotiations.
On 8 July 2011, the Security Council determined that the situation faced by South Sudan continued to constitute a threat to international peace and security in the region and established the United Nations Mission in the Republic of South Sudan (UNMISS) to consolidate peace and security and to help establish conditions for development.
Having determining that the situation faced by South Sudan continues to constitute a threat to international peace and security in the region and acting under Chapter VII of the UN Charter, the Security Council by its resolution 1996 (2011) PDF Document of 8 July 2011 established the United Nations Mission in the Republic of South Sudan (UNMISS) for an initial period of one year as from 9 July 2011 with the intention to renew for further periods as may be required.
More recently however, as of the 2nd of December 2015, a UN peacekeeping chief has called for more peacekeepers to be deployed (adding to the over 12500 personal currently on the ground) due to both sides violating the ceasefire repeatedly, threatening all the progress it has made towards political