The toughness in SSC CGL is greater than that of Railway examination. So if you are preparing for SSC CGL then you will have a good strength in subjects such as Mathematical Ability, English etc. But the logic reasoning in Railways is a bit different from SSC CGL but if you practice well those can be easily equipped.

For banking examination, I would say,  preparing for it separately is important. In banking examination, the problems of Data interpretation comes which are not included in SSC. So if you want to appear for Bank then I would say you should focus separately on it. Also the arithmetic problems in banking exam are more elegant than that of SSC so to do bank you should focus separately.

You can visit the link below for the Preparation tips of SBI PO:

https://competition.careers360.com/articles/sbi-po-preparation-tips

To know about the preparation tips of SSC CGL visit the link below:

https://competition.careers360.com/articles/how-to-prepare-for-ssc-cgl

To know more about preparation tips of Railway visit the link below:

https://competition.careers360.com/articles/railway-exam-preparation

I hope this answer helps. All the very best for your future endeavors!