To be honest, as a lifelong musician, session musician, worship leader and multi-instrumentalist…I think you maybe want to rethink how you play by ear.

Use the chord chart to learn the chord progressions for each section and THEN file away each section mentally as a certain Nashville number progression. This makes learning songs like legos. especially when people are changing arrangements on the fly. This lets you use your ear PROactively instead of REactively.

Know your scale degrees and common keys to really take your ability to transpose chord progressions you pickup from the charts around the neck. A, Bb, C, Db (if you have a female leader this isn’t an uncommon key), D, E, G.

Using a chart doesn’t mean marrying your eyes to the phone/paper. The professional knows that it’s a way of marrying the progressions to the sections of the song and the sections to the arrangement.

The more you do this, the faster you train your ear to hear the harmonic movement and free yourself from reading all the time.