Is it “double-dipping” to give both an overal minus 50% for preparation required and 2 points cost per 1 point in slot?

B114 mentions “Preparation Required” as a limitation. One option that seems to fit my campaign design is:

1 hour [of preparation gives a] -50% [cost savings] 

GURPS Powers mentions that Modular Abilities can have various costs, if rearranging powers is costly, slow, and subject to disruption. What exactly do all of those three items mean? By “costly” we must mean that it costs some kind of resource, such as fatigue points, money, special equipment. By “slow” we get mixed up with the “preparation required” delay.

Page 63 says:

The GM may invent other forms. Set the per-slot cost to reflect the scope of  available traits: 4 points for a short list, 5 points for a lengthy catalog, 6  points for nearly anything, and 7 points for anything. Cost per point in  a slot should be 2 points if rearranging points is costly, slow, and  subject to external interference; 3 points if just two of those; 4 points  if only one of those; and 5 points if none of those. ... Many fictional users of Modular Abilities require supreme concentration  and effort to rearrange their abilities. Represent this using Costs  Fatigue, Requires (Attribute) Roll (p. 112), and Takes Extra Time. 

In my planned campaign, Takes Extra Time might not be appropriate, because a lot of the abilities in question are things like invisibility, that can be prepared long before combat start, and Takes Extra Time can only be used for a few special cases:

Takes Extra Time  You can only apply this limitation to abilities that require time to  activate and that work fast enough to be useful in an emergency  (e.g., combat). 

My first thought was to give Modular Abilities limitations including Unreliable, Preparation Required, and Costs Fatigue. I think these would be applied to the reconfiguration process. I imagine that these would justify making the abilities cost 2 points per 1 point of power in the slot. However, the “Preparation Required” gives a major cost savings for the overall cost of the power, and thus assigning a cost of 2 character points per 1 point in slot might be double-dipping.

Question: Does this count as “double-dipping”?