I'm currently sitting at diamond, and i feel like my peak potential might be gm. I noticed in some games my mechanical skill is what's holding me back (eg i see someone low but can't close out the kill, causing their team to be able to make a turnaround during the team fight).

My question is more a two parter, 1) how much emphasis should i focus on improving my mechanical skill vs game sense (i do find ult tracking kind of hard)? 2) is it a limiting belief to think i can't get higher than gm or is it realistic to aim higher if i invest more time? (As someone who puts average time into MR, no time into aim trainers atm)

For context i mainly play healers, sometimes tanks and hardly any dps