Processing time trends for 189, 190, 491 visas
Before the analysis, let me talk about one fundamental understanding and one assumption first.
The fundamental understanding is that the primary factor affecting processing time trend is the relationship between (a) the number of lodgements and (b) the number of grants for the same financial or budget year.
If (a) < (b), it means there will be less and less applicants competing for more available slots.
If (a) > (b), it means there will be more and more applicants competing for less available slots.
Is your occupation priority or regular? Are you onshore or offshore? Are you single or have dependent or dependents? These all matter, but these are all secondary factors, because they all operate within the hard constraints of supply (new grants) versus demand (new applications), so they only change the magnitude within the general direction.
The assumption is that this year, the number of 190 and 491 allocations will likely not change, perhaps a slight increase, but based on what have seen in TAS & NT announcements and the speculation that States and Territories are not happy with their allocations this year (as seen in the ISCAH post), the increase will not be significant, so the number of new applications lodged this year will only be slightly higher.
If the allocation numbers turn out to be very different, then the following analysis may become invalid.
TLDR:
This year, 190 looks very good, 491 looks not good, and 189 remains to see, depending on the invitation patterns.
If you have already lodged a 190 application, there is no reason to worry. There may be some delays, but everything is getting faster.