Believe it or not, even during the recent past, some salons did not use hair lighteners ( bleach) because they had witnessed broken hair or unattractive results when the toner they had chosen did not deliver what they expected.
NOW we see that bleach has become one of the most frequently used salon hair color products.
To most completely address all bleaching needs, be sure to stock both powder and Creme lighteners. My experience and education confirm that Creme lightener can 'lift' almost as much as powder lightener when it is mixed with 49 volume developer, AND Creme is the safest and most effective type of lightener when on-scalp. 'Global' Blonding is your plan.
Remember, also, that most lighteners work for up to two hours, but that the 'fastest' lift happens during the first 60 minutes. And the finer you section each strand you select, lift will be more effective and able to bleach the hair most effectively.
When using high lift shades of permanent hair color, the best results are obtained when the formula is left to process for One Hour... at room temperature. And, as you know, high lift blonde shades DONOT cover gray. Their job is to lighten hair and to create a soft final tone. Best results can be expected when a client's hair is level 6 and lighter, and when the client has gray, blue, or cool green eyes...