In short: A man who has everything is missing a surprise, not things. Three kinds of gifts still work: one he cannot buy himself (a small, numbered edition), one chosen for him (a name, a date, a handwritten line), and one he will use every week. If you have little time, buying is fine, as long as the gift still feels chosen.
Something he can't buy himself
Anything on a shelf, he can buy tomorrow. A small, numbered edition he cannot. Just check that the limit is real, with no refills.
Something chosen for him
A name, a date, a handwritten line. Personal beats pricey. It tells him you thought about him, not about the price tag.
Something he will use
Another watch goes into the drawer. A sweater, a bag or a good pair of gloves gets used every week and keeps the gift alive.
If you have no time
Buying is fine, if the gift still feels chosen. Spend a little more on the part that makes it personal and rare.
More ideas: The Gift Nobody Else Will Give Him.
A note on transparency: we make a cashmere sweater ourselves, limited to 25 numbered pieces. The ideas above work for any brand. Our sweater is one of many you can compare.