unless sufficient time passes after leveling off at cruising altitude
While there is bound to be a system somewhere to prove me wrong, I don't think the statement is reasonable. Maybe another OWT at play ?
The whole idea of a venting system is to keep the in/out pressures as near to the same as practicable (noting FE Hoppy's comment re slight positive diff, below).
If that doesn't happen, undesirable things can happen if the diff gets too high (forces on a bit of tin relate to pressure diff across the area of the bit of tin).
Plenty of examples around ..
(a) tanks crushing due to vent obstructions
(b) a C130 incident I can recall where an ill-considered short term mod (the problems of "it's got to be done now" can lead to checks and balances in the decision process being omitted) left the external tank unvented and, you guessed it, all crinkled up at the end of the flight (read "embarrassment" and "dollars").
etc.