The holiday shopping season came in two parts, with a lull in between.

A spending surge in the two weeks before Christmas, coupled with a record-breaking Black Friday, gave retailers solid numbers. The doldrums between the buying binges showed how shoppers have learned to wait for the discounts they know will come.

For Dec. 1-24, spending rose 4.7 percent compared with the same period last year, according to the research firm ShopperTrak. In November, it rose 4.1 percent. A 4 percent increase is considered a successful season; a combined figure for the entire season won't be available until after Dec. 31.

The increase is good news for the economy because it shows shoppers were willing and able to fund a holiday splurge. Consumer spending, including major items such as health care, accounts for 70 percent of the economy.

Still, plenty of people remain pinched for cash and seeking the best deals. And stores have trained even shoppers primed to spend to look for discounts.

In the seven days before Christmas, last-minute shoppers gave retailers a 4.5 percent increase in revenue at stores open at least a year compared with the same week last year, according to the International Council of Shopping Centers-Goldman Sachs Weekly Chain Store Sales Index, which estimates sales at 24 major stores, including Macy's and Costco.

Total retail revenue for the week ended Saturday rose 14.8 percent compared with a year ago, ShopperTrak estimated.

Gift buyers gained steam as the season went on. The store-revenue figure rose 0.9 percent last week from the week before, building on a 3.4 percent increase the prior week.

"The downs and ups were much more accentuated," said Michael P. Niemira, chief economist at the trade group. "It just shows how cautious the consumer is. Consumers are bargain-hunters more today than ever before."

The post-Black Friday lull was deeper than usual this year. The two weeks after Thanksgiving weekend showed the biggest percentage sales decline since 2000. Then, in the final two weeks before Christmas, sales surged again, by the highest rate since 2005, Niemira said.

"The holiday season was good but uneven," he noted.

Stores are expected to benefit when shoppers come back to spend their gift cards, because people often spend more than the cards' value. According to an ICSC-Goldman Sachs survey of shoppers conducted Sunday, 18 percent of holiday spending went toward gift cards, up from 14.6 percent last year.

A fuller holiday spending picture will come Jan. 5, when stores including Target Corp. and Macy's release December sales figures.

Online spending from November through Dec. 26 increased 15 percent over the same period last year, according to comScore Inc., which tracks retail e-commerce activity. The biggest single-day bump was on Black Friday, when U.S. consumers spent $816 million online, a 26 percent increase over the $648 million spent in 2010.

For Nov. 28, Cyber Monday, when post-Thanksgiving bargains were heavily marketed online, sales were up 22 percent, comScore reported, reaching nearly $1.3 billion.

Inquirer staff writer Maria Panaritis contributed to this article.