Huge productivity boost with onFocus and onBlur

I inherited an old web interface, that used default values in form input fields as follows:

<INPUT type="text" name="username" value="Please input a username">

I have now changed it to the following

<INPUT type="text" name="username" value="" onblur="if(this.value=='') this.value=this.defaultValue;" onfocus="if(this.value==this.defaultValue) this.value='';">

Time spent for this change: ~2 mins, today
Time saved from this change: ~30 mins per day, every day
Keypresses and mouseclicks saved from this change: ~150 per day, every day