Of course, like you mentioned, there has to be a decline in value (preferably 80% or higher) - which signifies the ending of one price cycle and the beginning of another. But the thing is, with the ending of every price cycle - the next one becomes less and less likely to occur, or takes a little longer to occur... which is why accumulation cycles tend to become more extended over longer periods of time when you are dealing with older, more established coins.
So the older a coin is it will have higher sell pressure?
Why is this?
Every time you buy a coin that has good price run your profit comes because of people who don't know what they are doing buying at the top when the price is climbing,
they time their trades in such a fucked up way that it's impossible for them to make money
then when the price crashes because of profit taking, they still put sells at the previous price levels to break even or score a tiny profit
this is like a residue of sell resistance left behind after every up move
so the more price cycles you can see on the chart you will have a build up of sell pressure from all the previous cycles