No

//button[@id='timeout-btn']

Without index, the locator is returning a list of 4 elements

Yes

(.//button[@id='timeout-btn'])[1]

With index, the locator is returning the required value

<input _ngcontent-bxt-c188="" matinput="" type="text" class="mat-input-element mat-form-field-autofill-control ng-tns-c58-23 cdk-text-field-autofill-monitored cdk-text-field-autofilled" id="mat-input-5" aria-invalid="false" aria-required="false"/>

//input[@id="mat-input-5"]

ids such as "mat-input-5" are often not reliable. Sometimes they change after navigating through the page. It is better to not use them as an identifier.

Using an XPath can be more reliable in such cases

<button _ngcontent-bxt-c188="" mat-flat-button="" color="primary" id="login__submit" class="mat-focus-indicator ng-tns-c188-22 mat-flat-button mat-button-base mat-primary">

...

</button>

//button[contains(@class,"mat-flat-button mat-button-base mat-primary")]

<div class="mat-form-field-infix ng-tns-c58-4">

...

</div>

//div[@class="mat-form-field-infix ng-tns-c58-4"]

<div _ngcontent-jfq-c196="" class="form__checkboxes form__container">
<h2 _ngcontent-jfq-c196="">Please select all names below, you might consider using for your next pet:</h2>
<mat-checkbox _ngcontent-jfq-c196="" class="mat-checkbox mat-accent" id="mat-checkbox-2">
</mat-checkbox>
<mat-checkbox _ngcontent-jfq-c196="" class="mat-checkbox mat-accent" id="mat-checkbox-3">
</mat-checkbox>
<mat-checkbox _ngcontent-jfq-c196="" class="mat-checkbox mat-accent" id="mat-checkbox-4">
</mat-checkbox>
</div>

When the following element is already defined:

<element type="mat-checkbox" id="charlieCheckbox" attribute:id="mat-checkbox-2"/>

//mat-checkbox[@id = 'mat-checkbox-2']/following-sibling::mat-checkbox[1]

<li>

<a id="navigation.ticketOverview" href="" />

</li>

//li[a[@id="navigation.ticketOverview"]]

//img[@alt="Charcoal"]

To identify the image with alt attribute

id is used in the scenario / step 

//a[@id='swatch17"

To identify the link (a) with an id attribute

'id' (not the attribute:id) is used in the scenario / step

//a[contains(@class,"

^{swatch-link-92 has-image}

")]

The class can be a good choice to identify a page element. Make sure it is unique and if you use just part of the classes, also include the method="contains"

When there is no unique identifier we can build a path to locate the element. We can add an attribute check for each level, but the 'id' must be on the element  we want to use in the tests

To identify the image with alt src is not recommended. Just imagine if we have more environment, the link will change

href is generally not a good idea to use for same reason as src for img. Neither java script functions, it can be more than one on the page and also can be changed.

can be a good choice if it is unique and the page is not (and won't be) translated to other languages where this attribute can be different

with generator="css" we can force to use the css selector like By.cssSelector: div[id = 'mat-select-1-panel']

<div id="" attribute:class="SearchButton" method="contains"/>

Given 2 scenarios created:
This is the first example
This should be the second example

When:

1. you create the locator in CAST from this xPath which is btw not working on the UI, only with CAST with text: //span[containsWord(text(),‘is’)]
   to this:
   <span id="exampleTextSpan" text="is" method="containsWord"/>
   
   
   

2. you get the text with sui:get-text like this:
   
   

   ^{<sui:get-text pageId="exampleTextSpan" name="exampleTextSpanOutput"/>}

3. and you create an echo about it like this:
   
   

   ^{<echo message="+++++ exampleTextSpanOutput: ${exampleTextSpanOutput}"/>}

Then the echo will give back to you only 1 result and the echo will be this:

+++++ exampleTextSpanOutput: This is the first example

containsWord finds only the one word which contains exactly the word in this case "is", not that "is" word which is inside the "This".

As an FYI info:

1. if you have these 2 scenarios

2. and if you change the text in the locator from text="is" to text="xxxxxxx"
   
   

3. then the test will fail because it doesn't contain anything like the "xxxxxxx" and the auto-generated XPath by CAST will be this:
   //span[contains(concat(' ‘,normalize-space(text()), ’ ‘), ’ xxxxxxx ’)]