Most magnetometers in use by the community employ a superconducting magnet, which showing the four measures of the rate: τ * -1 , τ mode -1 (Eq. 7), ⟨τ⟩ -1 (Eq. 8 ), e -⟨ln [τ]⟩ (Eq. 9 ). constrains the maximum sweep rate to < 0.1 T/s and hence the switch-off time of the saturating field is non-negligible (Fig. ). If the magnetic relaxation timescale τ is short compared to the sweep rate of the instrument, many of the moments in the sample would have equilibrated in this time period and their relaxation is not observed: this does not present an issue if there is no distribution in the sample (as a mono-exponential decay appears exponential at all points in the decay), however in the presence of significant distributions then the measured data are skewed to the more slowly relaxing part of the sample. Further exacerbating this effect is that often the first measured point is subject to a wait command until "field stability", which can take a further 10 s before measurements can begin (Fig. , Table. S10). Another experimental concern is that the target field may not be accurate -superconducting magnets are well-known to trap residual fields, meaning that "zero-field" is not necessarily zero: hence, field calibration is essential for accurate data. Furthermore, in the case of samples with very slow dynamics it may not be practical to measure the entire decay curve, and in the presence of distributions this has an impact on the results. Finally, the application of Eq. 3 for fitting the data (i.e. fixing or freely fitting certain parameters) also affects the extracted values of τ * and β . Therefore, here we will also examine all of these experimental considerations and propose a set of guidelines to obtain high-quality magnetisation decay data. Samples are saturated at high magnetic field before the the field is swept to the target field. In a Quantum Design MPMS3 the fastest field sweep rate is 700 Oe/s, such that it takes ≈ 100 s to go from 7 T to 0 T. The x-axis is set to t = 0 s at M 0 , and M eq is not shown on this scale.