Not a requirement of any sort, but it does help maximizing profit, especially when BTC is rising quickly and Alts are dropping. The more the bot can buy going down on a bear trend, the better it is in terms of risk mitigation and profit returns in case of an Alt markets recovery for example. Note that in a bear trend a lower aggression settings is advised, you don't want to spend your basecurrency too fast.
Besides adding more funds, starting with less than 100% allocation and increasing your position during bear trends could also add to better results. (e.g. Start with only 60% of your funds allocated and at the end of, for example, a BTC rally you put your allocation to 100% to profit from the possibly fallen prices of Alts.)