You talk about how efficient it is, but you forget it does not transfer healing to you beacon(s). If you have faith that's 32% on two targets of the amount healed or 40% with BotL. With mainly healing through LotM your losing a key ability that makes up most of our healing and allows others to not really worry about tanks as much and focus more on the raid.
The reason you feel like yours doing so well is you are able to snipe heals. Maybe with your previous spec you had trouble gauging who needed healing and would hit targets some one else would heal first. But now that your instant casting you get the heal first.
The only time I use LotM is when I have more hp then others and I have to move or in Mythic+ to avoid drinking and allow chain pulling by using it on tank. It is a tool to be used but not as our goto tool.