Ditto, all these games it's always just been 1 gift a day. Though I did once give a girl 2 gifts because the first one put her right on the edge of gaining another FP. The second gift was just enough to push her over.
In general though, the gain is significantly less on the second gift so as to not make it worth it.
It helps when it's an item they like. I wanted to get Lara's shop to full stock, so I grew some strawberries in the green ruins and harvest the 9 and gave them to Lara each day (had a couple areas in prosperity)...The 9 would give about 3/4 of a friend's bar. Not great, but not bad for the minute it took to harvest and give them to her. Did the same for Rosetta.
Estelle: "They're bouncing..." Judith: "What are you looking at ?!" Estelle: "I wish I could bounce..." -Post Battle, TO Vesperia