SIPs are pretty flexible. One can increase, reduce, or even stop SIP investments at any point in time. This makes it an extremely flexible investment product. Most mutual funds also offer the facility to top-up SIPs, so one can make extra investments whenever possible, without disturbing the original SIP.
No Market Timing Requirement. Market timing is a tough job even for professional investors. The SIP does not require any market timing because investment costs are spread out under different conditions of the market. Consequently, market fluctuations reduce the influence to allow investors to construct stable portfolios without excessive preoccupation with daily price movements.