Books on Tibetan meditation process (Mahamudra tradition or school of practice).
includes a systematic process for the use of techniques during each phase of progress.

Tibetan traditions and schools are unique in that they always start to teach a “bibliography”.
The bibliography is a way of giving honour or credit or recognition or gratitude to the teachers within their lineage of traditions and practices.
They mention their Guru (Lama), their Guru’s Guru (Lama of their Lama), their Guru’s Guru’s Guru (Lama of their Lama’s Lama) and so on exhaustively…along with any new practices that evolved during each Lama.
All Tibetan lineages of traditional practices, trace their origin all the way back to Kashmir and acknowledge Shiva’s techniques as the origin.

Many people are unable to read past the first chapter simply because the “bibliography” is full of obscure names.
To the Tibetan, these names (characters and events and achievements) are familiar within their tradition and social fabric.

The Mahamudra tradition includes preliminary practices of cleansing (including action, thought etc.)
Subsequent phases of progress include self evaluation and (even more important) an evaluation by their Guru or Guide.
It is generally understood that progress to a higher phase will not prevent from “falling” back to a previous lower phase.
It is accepted that some practitioners are able to progress faster, however this is more about the exceptional person.