How can I find the appropriate level for determining the total wavelet energy?

As it is known, after determining the energy density function from:

E(a,b) = |C(a,b)|^2

The total wavelet energy (TWE) is determined as follows:

Where the signal scale is limited by the maximum value, denoted as a(max), we can lower the level number to decrease the runtime. However, Changing the level number will cause a corresponding alteration in the TWE value. What level should be used to determine the TWE for this specific purpose?

Sincerely.