It may seem sometimes in the early years, for other reasons (because yogis are having lots of tension) I encouraged yogis not to concentrate in the sense of having too much concentration.
But samatha is a practice that is taught by the Buddha; it is a valid practice. Samatha is also only done correctly when the mind has the right attitude, just like vipassana. When samatha is done correctly, the mind is balanced, clear and strong, just like vipassana. So, samatha is not a practice that I discourage. Samatha is a practice you can use if you want to. It is a practice that I still use. You must know how to use it; you must understand the purpose of it.
Samatha practice is used to calm the mind when the mind is overly agitated. If a yogi is very agitated and he can’t have the right attitude, then go back to anchoring the mind on one object; stop thinking about it and concentrate on one thing.
So, when yogis cannot bring on right attitude – the mind is too angry, too confused; when the mind cannot have right attitude at all – keep stopping the thinking and keep coming back to one object, keep anchoring the mind. If the mind cannot think, the feelings will subside.
When the mind has enough wisdom – even though the mind is confused, having anger or excessive greed – it can intellectually tell itself to watch the defilement in a balanced way. If there is enough wisdom, it can do it; but when there is not enough wisdom, it cannot bring on right attitude. Then it must rely on watching a neutral object.
Some yogis find that when they try to observe defilement, they resist the defilement because there is too much identification. When there is so much resistance, it’s better at that time to calm the mind first and then try to watch the defilement again.
You can use metta, Buddhanusati, or any of the 40 samatha practices