The pirates would often bury gold in the cave and then fail

would可用于表示过去经常性的行为或动作：
例：The retired captain would sit hours on end watching ships sailing past.（退休的船长经常坐在海边观望过往的行船,一坐就是几个小时.）
He would go to bed strictly at 9, and on Sundays would not have lunch anywhere except in that restaurant.（他总是严格地9点上床睡觉.星期日总在那家饭店吃午饭.）