The Bible can be a complicated book and hard to understand at times. Reading it in a year is a challenge and you may encounter verses, chapters, and maybe even books that are confusing. As a result, this sometimes leads us to look towards outside sources for guidance. There is nothing wrong with many of these sources, but we should not let them influence us to taking their words as gospel.
Every student of the Bible, and as a Christian you must be a student of the Bible, needs to develop the skills to think, reason, and analyze for themselves. (1 Cor 14:33) It does not mean one should not use helpful sources outside of scripture, but they should first gather their own opinions. Critical thinking is a crucial skill for the Christian to develop. Without it, it is too easy to be lead astray. (Matt. 7:15)
How do we develop those skills though? Firstly, we need to recognize the Bible as a tool. (Ps. 119:34; II Tim 3:16) While it can be overwhelming and confusing, it also does a superb job of explaining itself. This may not always be easily seen, but when the Bible student begins making small connections in the scripture, over time, they will develop skills to make the bigger connections as well. (Matt. 7:7)
Again, there are some useful sources outside of scripture that have been developed by wonderful people. But there are also sources that are less than reliable. The faithful Christian should always dive deep into a Biblical study before turning to outside sources and they should never take uninspired writings as gospel. (I Jn. 4:1; Phil. 4:8-9)