Eighty-two percent of Americans in a new survey said they give to charity, RBC Wealth Management–U.S. and City National Bank reported Wednesday.

At the same time, 47% of donors said they give sporadically, rather than at a planned interval or for a seasonal occasion, which may lessen the benefits both to themselves and the charities they support, according to the study.

“A well-planned program of lifetime gifts to family, friends and charities can provide income and estate tax benefits and help preserve more assets for heirs,” Van Pate, a wealth strategies consultant at RBC Wealth Management–U.S., said in a statement. “Taking a deliberate approach to giving can help you make well-informed decisions and increase the benefits to both you and the recipients of your good will.”

American donors also prefer to give broadly rather than to support a few causes, the poll found. Fifty-three percent of respondents said they gave to three or more charities, and 10% of this group donated to as many as 10 nonprofits. Four percent typically supported 11 or more organizations.

Millennials in the survey were more focused in their giving than their older counterparts. About a quarter gave to just one or two charities, while 6 in 10 donors 55 and older gave to at least three organizations and 7% gave to 10 or more.

“It’s common to believe that by dividing up our donations to help more charitable causes, we have the greatest impact,” Malia Haskins, an RBC wealth strategies consultant, said in the statement. “But there is a strong argument that, if you’re interested in doing the most good, you should concentrate your giving on one, maybe two organizations.”

Eileen Heisman, president of National Philanthropic Trust, a donor-advised-fund sponsor, agrees. Her rule of thumb on giving: Give fewer, larger grants and stay with the organization for a long time; don’t be fickle.

“Organizations have a hard time finding predictable income sources, and when they know you’re going to be around for a while, they spend less on overhead raising money,” Heisman told ThinkAdvisor in an interview.

Ipsos conducted the online poll with a sample of 1,005 American adults on behalf of RBC in mid-September.

Giving Dynamics

The poll identified several gender and regional differences in how Americans give. Eighty-six percent of women said they found charitable giving personally important, compared with 77% of men who said this. But men gave considerably more, on average, than women: $1,143 vs. $722.

Donors in the Midwest, who gave $1,111 on average, appeared to be more generous than their counterparts in the South, who gave $908, in the West, $906, and the Northeast, $743.

Yet, when pollsters asked how the total amount they planned to give in 2016 would compare with the amount they gave in 2015, 20% of Northeasterners said it would likely increase. This compared with 17% of those in the South and 15% in the West. Just 10% of Midwesterners said they would increase their giving this year.

As to the causes poll respondents were likeliest to support, 32% said they were drawn to organizations that help children—with parents much likelier to want to support children’s charities than those without children. The same dynamic held for charities focused on education.

Moreover, giving to children’s causes attracted 38% of millennials and 33% of Gen Xers, compared with 25% of baby boomers. And millennials were twice as likely as Gen Xers and boomers to give to charities supporting education.

Meanwhile, 22% of boomers said they were likely to donate to religious causes, ahead of 17% of Gen Xers and 11% of millennials.

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