Pumps do happen sometimes to altcoins on bearish times but not that often and it barely even lasts long. I personally don't bank on such altcoin pumps on bearish times. Chasing pumps is already too tedious and draining on a bullish market. Just imagine how hard it would be on bearish times. I'd rather use my extra funds for buying good coins that I like or DCA on the ones I already have. Not only does this make my crypto life easier, it also saves me from all the stress and potential losses. Still though, if you have the time to keep track with the news and other updates about the pumping coin you wanna chase and are pretty confident with your capabilities, then it's worth the shot.