Air carrier First Officer reported while on visual approach; pilot flying decided to descend to FAF altitude early; resulted in ATC issuing a low altitude alert. First Officer stated more training was needed for visual approach techniques.

Narrative

On arrival into BWI; we were given a heading off of the arrival towards the final approach for 10. We were then cleared the visual approach to 10. The Pilot Flying elected to descend down to 1500 ft. MSL approximately six to seven miles outside of JEANS. I looked at the map to make sure we were clear of the Tower at 958 ft. N-NW of JEANS and we were going to pass well to the west of that Tower. I thought the technique was legal and after confirming our position; relative to that Tower; safe; but sloppy and unnecessary at best. We were then switched to Tower and Tower immediately issued a Low Altitude Alert. I again referenced the map and saw nothing but green on the map; and we had not descended any lower. I assumed we had gone below the MVA for that sector with the Tower north of course; but were in a safe position to land. Landing was normal.After landing we discussed what had happened and the PF stated that he believed we were safe.The ATC call was unnecessary. This highlights a common problem I see with how we fly visual approaches. Pilots are just selecting the final approach fix in the FMS to L1 for guidance and disregarding other fixes and their corresponding altitudes; no matter how far from the FAF we are. Common sense and operating to the highest level of Safety would say outside of six miles from JEANS we should be at a minimum of 2500 ft. per the altitude at COLUM. Pilots are disregarding and/or not cognizant of obstacles and terrain that we would be protected from; by following the altitudes published further out on the charted approaches we reference for visual approaches. I would like to see more training on visual approach techniques and maybe even a requirement to sequence referenced charted approaches to the closest fix not just the FAF.