The official source

The appropriate reference for credible insights into indulgences offered and the prerequisites required for them is “The Enchiridion (Handbook) of Indulgences” issued by the Church initially in 1968 (and revised on several occasions). Concerning the Rosary, the following is relevant:

“A plenary indulgence is bestowed when one devoutly utters the Marian Rosary within a church or an oratory, or among family, in a religious group, in a community of believers, and, broadly speaking, when numerous individuals unite for a noble purpose. … A partial indulgence is provided under different conditions. The Rosary consists of a specific structure of prayer, featuring fifteen decades of ‘Hail Marys’ with an ‘Our Father’ preceding each decade, during which the recitation of each decade is paired with contemplative reflection on a particular mystery of our Redemption. … Reciting just a third part of the Rosary is sufficient; however, the five decades should be recited consecutively. The spoken recitation must be coupled with devout reflection on the mysteries. In communal recitation, the mysteries should be proclaimed per the local customs; for private recitation, it is adequate if the spoken recitation is paired with meditation on the mysteries …” (No. 17.1).

Here is the definitive and authoritative response, which should serve as the foundation for any conclusions regarding particular circumstances. Divergences from this standard, even if sincerely believed, lack legal weight and are incorrect. Therefore, your friend appears to be mistaken about the exponential increase of indulgences, assuming your account is correct. No such amplifiers are referenced in these standards.

Praying alone

Moreover, although there is a distinction between individual prayer and communal prayer, the norm allows for the opportunity of plenary indulgence when praying the Rosary (even when done solo) in a church or oratory. It also permits the potential for a plenary indulgence in group settings outside of a church or oratory when individuals assemble collectively “in the family, within a religious community, in an association of the faithful, and, broadly, whenever numerous people gather for a commendable objective.” Indeed, coming together to pray for the sick and elderly in a nursing home constitutes a gathering for a virtuous cause and can earn the faithful a plenary indulgence, provided that all conditions are met.

Reciting the Rosary by oneself, away from a church or oratory (for instance, at home), does not appear to grant a plenary indulgence. indulgence associated with it. The guideline states, “A partial indulgence is granted in different situations.” Nevertheless, regarding this “disheartening” is likely an exaggeration. Obtaining a plenary indulgence in any scenario is not simple as it necessitates, among other factors, a complete detachment even from all minor sins. Therefore, while pursuing plenary indulgences is always beneficial, partial indulgences hold significant value and tend to be the more likely outcome, even when plenary indulgences are available. Ultimately, the essence is that various forms of prayer greatly benefit both souls on earth and those in purgatory. Assist souls in every possible and sensible way!