Pick up summon have less unit in gacha pool because most of plats and blacks are removed.

Current pick-up Summoning Units:
Black:
Shaman Kikyou
Dark Fighter Cornelia
Witch Despia
Pegasus Rider Esther
Angel Sophie
Plat:
Vampire Hunter Elizabeth
Archer Victoria
Ninja Hina
Dancer Marnie
Pirate Anelia

If you dont have above units and wants some of them, its better to roll this one.
The rate is same with normal premium summon.