When weather-stripping can be applied in such a way as to compress between the frame and the moving door, window or trap, without any sliding action, it will seal better and last longer.
-- Simple foam tape is quite effective for the attic trap if it is put on the frame and the trap falls flat onto it and is clamped down tightly. Fancy sliding gaskets are less effective and do not last as long. Foam tape comes in many sizes and densities -- use the widest and densest that space will allow.
-- Doors warp with changes in climate, so good weather-stripping must be compressible, to take into account small warp differences between day and night, and adjustable, to take into account a larger warp movement that starts in the fall and returns in the spring. Rigid backed rubber is good -- the rubber gives with small changes, while the rigid backing has slotted screw holes or is spring loaded for seasonal adjustments.
-- Spring metal or vinyl weather-stripping placed on the fixed frame slides a little but mainly compresses. This action allows for both minor and major door warping without too much wear.
-- Metal door will have magnetic weather-stripping much like you will find on modern refrigerators. This is extremely effective while requiring little pressure to open or close the door.
-- With the exception of the spring metal or vinyl techniques, doors and swinging window frames should be arranged, if possible for compressive weather-stripping rather than wipers. On the hinge side, this means putting foam tape flat on the fixed frame (not on the stop, as on the other sides) or rigid backed rubber strips on the moving frame or door itself to push against the stop (rather than on the stops to push against the door or window). It doesn't look as good this way but it works better and lasts longer. After years of pushing this, I was pleased to see some companies suggesting this as an "alternative" to the standard techniques.
-- Good door sills can have compressive or interlocking weather-stripping, although because these tend to jam up with snow or dirt the less efficient sweeps are more commonly used.
Weather-stripping a sliding joint involves more work and expense, and yields poorer results than weather-stripping a compressive joint. The fact that the joint must be loose enough to slide counts against you to start, and the sliding action rapidly wears the weather-stripping.
-- Fancy and effective sealing systems exist for weather-stripping the old double-hung, wooden-frame sliding windows, but they require a cabinet-maker to rework both the window and the frame -- maybe not worth the trouble.
-- Spring metal or vinyl strips can be effective in wooden sliding windows if you have room for them.
-- Foam tape at the end of a sliding run (horizontal or vertical) can provide a compressive seal for at least one edge of a window.
-- Most modern sliding windows have replaceable felt or rubber wipers. Keep them in place (they often slide around) and replace them if necessary. If you have sliding windows in a metal or plastic frame that has no provision for wipers, replace the window.
-- Most door seal wipers have replaceable rubber elements. Refuse to buy it if the store doesn't stock the replacement parts. Buy an extra with the first purchase, so you don't go half the winter with a draft under the front door because the rubber walked away.