I have seen some of the older men in my family who were born in Tunisia that do not take their watches off when they put their tefillin on. When I asked them how come they leave on their watch the answer was
"there can only be a hefsaik when you initially perform the (Lehaniaach) tying of the Retsuah on the upper arm."
They further mentioned to be extremely careful with your shirtsleeve to make sure the shirtsleeve does not sneak under the Retsuah when you are about to perform the (Lehaniaach) tying of the Retsuah on the upper arm with the Bracha.
They further mentioned, the watch down at the wrist is a non issue when it comes to a hefsaik between the Retsuah and the skin. They further listed different cities in Tunisia where they visited friends and family and all of the men did the same thing.
Essentially this was common practice "This is the way we have done it for 75 - 100 years, and that is that."
1. Is this common among other regional groups of Sefardim as well?
2. What is the common acceptance when it comes to watches and tefillin, today?