Modelling a phase shift signal that is delayed
Note that the phase shift related to the frequency (or 1/f = period) of your input signal. So for example: a 1 MHz signal has a T = 1/f = 1 us
A delay of 180 degrees then corresponds to 0.5 us

But the time delay of the delay block is fixed, it is independent of the frequency of your signal.You could express that fixed delay as a phase shift. For example, take a 0.5 us delay, that corresponds to the 180 degrees phase shift of a 1 MHz signal (see above).

But if the signal is 0.5 MHz, then T = 2 us, then that fixed delay of 0.5 us becomes 0.5 us / 2 us * 360 degrees = 90 degrees phase shift !