The two ways that you mention are part of the strategy that I use.
Long-term investments, in my opinion, are great to do.
Given that experience like the year 2017, it is able to generate many advantages.
But since 2018 many long-term investments experienced the dilemma as many coin selling prices declined.
Short-term trading is a great option for making a profit every day.
All very good to do only time and patience that makes you can make a profit.
Dividing your strategy from both ends allows you to generate decent profit. Choose solid projects for long-term investment then combine it with moving coins that you can sort for short-term or day-trade investment. You should have a good practice and a good setup of system that's able to differentiate these two types of investment process. Also a plus factor if you have the patience so you can apply the right attitude when you place your entry position both for short and long-term assets and stick with how you understand the system that you've created along the way.