Many macros consist of a sequence of show/execute menu items which could also be expressed as a series of keystrokes (app specific shortcuts, too numerous to remember) followed (or not) by a pause of variable length.
My suggestion is to create an extensible action which would allow me to :
1- enter a keyboard shortcut
2- enter a pause to the right of the shortcut
3- click on a + (step 3) if I want to enter another keystroke followed by a pause
and so on
thank you for considering my request
It is not impossible that I will add explicit control over the pause that happens after an action, but to a degree this goes against the philosophy of Keyboard Maestro, which is to break apart actions into their component parts rather than have actions with multiple separate things altogether (Quickeys tended to do this I believe, and it is a stumbling block for a lot of Quickeys users when they transition to Keyboard Maestro).
thank you.
to answer my own question, one option is simply to create a group, enter the app, the successive keystrokes and pauses and delete the superfluous actions
Another approach is to make use of the Set Action Delay action to set the Simulate Normal Keystroke Delay in the macro where you want this.
thank you for your suggestion. The problem is that the delays varies by a wide range from 0.2 to 2-3 seconds.
thanks again
You showed a constant delay in your example, so I was just following it. 
Yes, you are right. My mistake. A good reminder that I should spend a bit more time formulating my questions, and thanks again for taking the time to suggest an answer.
@ronald, n.p. It is actually difficult to formulate a good question, as evidenced by the many (usually not yours) poor questions that are posted. To be clear, most of @ronald's questions are very good.
Like with almost any endeavour (scientific, engineering, software development), the key to finding/getting a good solution is asking the proper questions.
My sincere appreciation goes out to everyone who takes the time to ask good questions. For help in doing this, see:
Tip: How Do I Get The Best Answer in the Shortest Time?
your text was very instructive, and I also had a look at a few macros on the same page.
thank you very much