It's your module, do what you like! You won't see a lot of code excluding imports. You will see:

use Module qw( :utils );
use Module qw( util1 util2 util5 );
use Module qw( :utils_basic );
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You can define any export sets you want. The bottom line is that it will make very little load/runtime diff if you import the extra unused functions.

Personally I generally shun import tags. I like to ask for each and every function by name as when someone else comes to look at the code it documents where the function lives ie which module:

use Module ':all';
use Other  ':all';
# etc

.....

func(); # "!£$^%^! where the hell did this come from?
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I like importing as it save long function names. It does make it harder to track the source module. ':all' or whatever makes it harder still.