Depends on the speaker mostly, and how much the cone moves.
If you your speakers have "long throw" woofers with excessive cone movement, re-foaming them will be a regular activity for you.
If on the other hand you own a pair of K-horns like myself, there won't be any need to re-foam because the cone never moves more than a 1/16th of an inch, worst case scenario. No movement, no wear!
I bought my speakers new in 1978, the access panel for the woofers have never been removed. Bass is as good as it was new...
If you your speakers have "long throw" woofers with excessive cone movement, re-foaming them will be a regular activity for you.
If on the other hand you own a pair of K-horns like myself, there won't be any need to re-foam because the cone never moves more than a 1/16th of an inch, worst case scenario. No movement, no wear!
I bought my speakers new in 1978, the access panel for the woofers have never been removed. Bass is as good as it was new...