Someone posted that lift & drag are interrelated - altering one alters the other - so talking about drag only is a nonsense.
Who posted that?
Lift and induced drag are related but airspeed is also a factor.
However, form drag or parasite drag or interference drag as examples have no relation to lift.
As an example that is common to your gliding and also powered flying;
If you fly with the wheel extended, drag will be increased but there will be no effect on lift. The extra drag will reduce the time you can remain airborne.
If you fly a B747 with the wheels extended, drag will be increased and the amount of time that the aircraft can remain airborne is also reduced.
So why is it that powered or not, it is drag that an influence on the time that the aircraft can remain in the air?
Regards,
DFC