Maybe over a decade ago, I used to worry about a long/big run up prior and maybe there isn't any meat left on the bone or the party is over or there isn't enough ammunition left for this stock.
In reality, there are waaaay more money sitting on the sidelines waiting for a good entry point and when the charts show a good setup, retailers that can spot it and institutions that scan it constantly will pile in for the easy money.
You want to be trading or buying bullish breakout setups over falling knife, swing trades or cheap stocks cos the latter 3 have a pretty high chance to be short targets or have 'lost interest' from institutional money.