I think, it depends on the price of the coin that I hold, if I get a profit then I will sell it but if I haven't got a profit then I will hold on and continue to wait until the price is high again.
Yes if you have invested in the right coin then you should not be worried about the temporary market slumps but if you have invested in the wrong coin obviously you will not gain anything and the more you wait the value will drop and it happened with my wherein I purchased an alt coin at $0.4 and I had to sell it for $0.08.