Hey popa, you got moderator privileges? So why don’t you fix up your subtitle?
Not trusting yourself is not quite the same thing as ‘moving toward the right’. Also, if every generation adds only one Gezeira – which is not quite the same as adding a Chumra – then obviously they will pile up.
I don’t know why you brought up Nida. That is in the Gemara, along with many other Gezeiros.
As far as finding a trend, I don’t think it is consistent. You can find things in old Tshuvos that really make you wonder what was going on.