Percentage deviations between our implicit (red solid) and explicit (blue dotted) diffusive mixing schemes with different timesteps. The deviations are taken for nitrogen abundances at the time of the evolution when the differences between that evolutionary sequence with the sequence with fixed timestep δt = 0.001 Myr is the largest. The model sequences are for a 20 M_⊙ star with initial equatorial rotational velocity of 300 km s^-1 with fixed shell mass δm = 0.05 M_⊙.