Stilton
re Thrust reversers, Not just "one slippery day"...every day!
For a start, idle reverse reduces the need for wheel braking to almost nothing on a limiting LDR x 1.5 (or better) runway at MLW for normal ops.
Additionally, there is a small factor to improve TORR and LDR performance with reverse and so, improve max operating weights and reduce operating base field requirements. The improvements to MTOW can be important where a base with limiting TODA/TORA must be used!
OAP