Penang Retreat 2019 Group 4 Round 4 (1:03:22-1:03:36)
My teacher told me to send metta to all beings after meditation because sending to all beings without choosing is paramattha metta.
When you choose to send to specific individuals, the metta becomes a concept.
Also, when you wish other beings to be happy and well, check if your mind quality is the same as the wish.