Back in the late 1980s my friends and I played a lot of ForeSight, which is a SF/GP RPG with a detailed combat system regulated by turns and a grid. We were most of us living and running our games in college rooms (dorms), or shared digs and family homes where we were lucky to get the lounge room, and seldom had the luxury of a dining table. What with one thing and another it always seemed like more trouble than it was worth to break out the hex grids, dry-erase markers, and tokens for what was likely to be a short and decisive fight. So we used the system of turns and discrete actions and the resolution systems of the game, but with only a mental map or a sketch on scrap paper, which went quickly and seemed satisfactory.
But after a while @frank.hampshire and I noticed that fights without a hex-grid were less varied and tactically interesting than those with, that PCs made took less advantage of position and manœuvre, and that PCs were in general noticeably less effective in combat. We tried to make it a custom to always use a grid, but couldn’t overcome the grumbling at set-up. Only semi-defeated, we promulgated a convention that any player is entitled to ask for the grid to be used in any fight, and that the GM ought not to do anything that would have a chilling effect on the exercise of this right. Frank and David Lawrence started work on a Miranda warning for players whose characters were about to enter combat, but it never got further than “you have the right to a hex-grid”.
Despite my earnest intentions and occasional extravagant preparations, like I suppose most of us I usually don’t bother to break out the battlemats, the hex-paper covered with acetate film or encased in clear PVC, the dry-erase panels with hexes painstakingly drawn on them with paint, the markers and the cardboard heroes. But I really feel that that amounts to my being too lazy to strive for the best results.