STRICTLY SPEAKING, there can be only one kind of Confraternity of the Rosary----one whose members agree to say the entire Rosary of one hundred and fifty Hail Marys every day. However, considering the fervor of those who say it, we may distinguish three kinds: Ordinary membership which entails saying the complete Rosary once a week; Perpetual membership which requires it be said only once a year; Daily membership which obliges one to say it all every day, that is, the fifteen decades made up one hundred and fifty Hail Marys.
None of these Rosary memberships binds under pain of sin. It is not even a venial sin to fail in this duty because such an undertaking is entirely voluntary and supererogatory. Needless to say, people should not join the Confraternity if they do not intend to fulfill their obligation by saying the Rosary as often as is required, without, however, neglecting the duties of their state in life.
So whenever the Rosary clashes with a duty of one's, state in life, holy as the Rosary is, one must give preference to the duty to be performed. Similarly, sick people are not obliged to say the whole Rosary or even part of it if this effort might tire them and make them worse.
If you have been unable to say it because of some duty required by obedience or because you genuinely forgot, or because of some urgent necessity, you have not committed even a venial sin. You will then receive the benefits of the Confraternity just the same, sharing in the graces and merits of your brothers and sisters in the Holy Rosary who are saying it throughout the world.
And, my dear Catholic people, even if you fail to say your Rosary out of sheer carelessness or laziness, as long as you do not have any formal contempt for it, you do not sin, absolutely speaking----but in this case you forfeit your participation in the prayers, good works and merits of the Confraternity. Moreover, because you have not been faithful in things that are little and of supererogation, almost without knowing it you may fall into the habit of neglecting big things such as those duties which bind under pain of sin. For----"He that contemneth small things, shall fall by little and little."  Ecclusiastics 19:1
From page 24 and 25
Nihil Obstat, Gulielmus F. Hughes, S.T.L., Censor Librorium
Imprimatur, Thomas Edmundus Molloy, S.T.D., Archiepiscopus-Episcopus Brooklyniensis, 1954 For more, see The Holy Rosary
St. Louis-Marie Grignon de Montfort's The Secret of the Rosary