The Aureole of Olmpus Mons is an example of major flank collapse of the volcanic constructs. This appears to have occurred in early Amazonian time, around 1.5-2.8 Ga.

Collapses of wallrock in Valles Marineris appear to have been steady to diminishing over a similar period, but studies of the mechanical strength of the walls show that they are quite strong and not weakened by any process.

The model of Mars as a cold frozen shell of permafrost many km thick, for at least the past 2-3 Ga has still to be dented by any evidence. Sure there have been ongoing volcanic eruptions and some localised outburst floods, but these are not typical of the planet as a whole.

Now, if you went back to the Noachian, 3.8 Ga+, things were a bit different. Mars was quite active then and all sorts of things were happening...