V来V去【lái qù】

One verb, repeated as V来V去, describes movement back and forth or an action repeated again and again. With a verb of motion, it is the movement itself: up and down, to and fro.

Over and over, with no result

With a verb like 想, 说, 找, 看 or 选, V来V去 means doing it repeatedly – and usually not getting far. A second clause often gives the outcome, with 还是, 也 or 都.

说来说去 has set as a phrase: "when all's said and done", "in the end".

Where the object goes

The object can't sit inside the frame. Put it first as the topic, or after a verb in the next clause.

• × 他找钥匙来找钥匙去 → 钥匙他找来找去也没找到
• × 我选衣服来选衣服去 → 我选来选去，还是买了那件衣服

The order is fixed too: 来 first, then 去.

• × 走去走来 → 走来走去

Here 来 and 去 don't point towards or away from the speaker, as they do after a single motion verb in 回来 or 进去.