  We present an analysis of the whole 2018 outburst of the black hole X-ray
binary MAXI J1820+070 with Insight-HXMT data. We focus our study on the
temporal evolution of the parameters of the source. We employ two different
models to fit the disk's thermal spectrum: the Newtonian model DISKBB and the
relativistic model NKBB. These two models provide different pictures of the
source in the soft state. With DISKBB, we find that the inner edge of the disk
is close to the innermost stable circular orbit of a fast-rotating black hole
and the corona changes geometry from the hard to the soft state. With NKBB, we
find that the disk is truncated in the soft state and that the coronal geometry
does not change significantly during the whole outburst. However, the model
with NKBB can predict an untruncated disk around a fast-rotating black hole if
we assume that the disk inclination angle is around $30^\circ$ (instead of
$\sim 60^\circ$, which is the inclination angle of the jet and is usually
adopted as the disk inclination angle in the literature) and we employ a
high-density reflection model. In such a case, we measure a high value of the
black hole spin parameter with observations in the soft state, in agreement
with the high spin value found from the analysis of the reflection features and
in disagreement with the low spin value found by previous continuum-fitting
method measurements with the disk inclination angle set to the value of the jet
inclination angle.
