By all the answers posted here, I think it's all hard work, study, practice, analysis, and other standard techniques mentioned to increase one's ratings.
Does this mean that a player's gut feeling, intuitive understanding of the position has no meaning?
I have started to take chess seriouly and would like to see myself 1800+ rated in 3 months time. I am not doing anything new like trainings, etc but have made a point to view the board more closely before making any move. Do you think in general, it is possible to move from 1500 to 1800+ in 3 months
No,
If you take chess seriously better to take the necessary time to train properly and get experience think more like 12-19 months not 3 months.