I have called him three times this morning. 事件发生三次。

I have been to Beijing five times in my life. 事件发生5次。

He has worked in this company. 本句为习惯意义，句子缺少持续时间状语。应该加since或for短语表示习惯的持续时间。否则为错句。

I've been there once or twice.  be there加了once or twice, 则转意为动态动词表示事件。相当于have stayed there, have visited there.

He's lived in London for quite a long time. live为静态动词，表示状态。不是习惯。

twice，three times，不能表示习惯，只能表示事件发生了多少次。只有加上单位时间才是频度状语表示习惯，如twice a week, three times a month等。often，sometimes为频度状语，通常和表示习惯意义的谓语连用。

I often met him when I was in London.这个句子是错句。时态错误。改正如下：

我在伦敦时，我经常见到他。(表示过去某个时期的习惯性动作）

We have often been there .这个句子很别扭。应改用其它动词和时态。例如：

We often go there. We often went there. 分别表示现在或过去的习惯。