“Strong-field” spin period evolutions: P(t) tracks for LSI permitting large polar field strengths, B _p ≳ 10¹⁴ G, as shown in the panel legends. Larger braking indices allow for ﹩\dot{P}﹩ to be relatively small at early times t ≤ 5 kyr (see insets, which display ﹩\dot{P}﹩ as in Figure 2). Propeller torques may activate at this fiducial switching time for an accretion rate ﹩{10}^{-6}\leqslant \dot{M}/{\dot{M}}_{\mathrm{Edd}}\leqslant {10}^{-5}﹩ (left panel) or the surface field may decay to a dipole-like configuration with 2.5 ≤ n ≤ 3 (right panel) to account for a large ﹩\dot{P}﹩ shortly after t = 5 kyr. We fix α = 0.