it was a sudden plan vs it was a sudden plan b

Examples:

• It was a sudden plan to go on a road trip.
• She came up with a sudden plan to surprise her friend.
• The decision to move abroad was a sudden plan.
• He executed a sudden plan to change careers.
• The sudden plan to renovate the house caught everyone by surprise.

Alternatives:

• It was an unexpected plan
• It was a spontaneous plan
• It was a last-minute plan
• It was an impromptu plan

Examples:

• When the first option fell through, they had to resort to a sudden plan B.
• She always has a sudden plan B in case things don't go as expected.
• The sudden plan B to relocate the event to an indoor venue saved the day.
• Having a sudden plan B is essential in event planning.
• The team had to implement a sudden plan B to meet the deadline.

Alternatives:

• It was a last-minute backup plan
• It was an impromptu backup plan
• It was a sudden alternative plan
• It was a backup plan decided on abruptly