Depends really. Older locks can be easier to pick since the tolerances become looser due to wear and tear over the years. As for the pins being harder to lift, this is down to buildup within the lock thanks to constant exposure to the elements. It dampens the feedback a little, but at the same time it's easier to avoid oversetting pins when they don't lift as smooth and light as they should. Although if there is a lot of buildup in the lock, pins which really shouldn't be binding can stick and overset, so determining the actual binding order is more difficult.
Another problem is that people are advised to lubricate the lock every x amount of time to keep everything smooth, but of course nobody ever does. Not a problem if you're using a key, but when picking, instead of the plug rotating nice and smooth, it has a slight drag to it. Because of that stickiness, if you do overset a pin, you can't lower your tension by tiny increments like you normally can, meaning you pretty much have to reset the lock.
If you're working on a lock which has been used outdoors for a long period of time and having trouble with it, you need to determine what's going on and use the appropriate stuff. A graphite spray will loosen up and flush out the debris which is in there, so if you have sticky pins, use that. If it's just a sticky plug, use a silicon based lubricant to get it rotating nice and smooth again. If you're dealing with a padlock though, a sticky plug is usually to do with the spring return and there isn't really any way around that so you just have to deal with it.
On that note, many cheaper padlocks use tighter springs, so don't confuse spring resistance with stickiness and bust out the lube straight away. Tighter springs give better feedback and make the lock much easier to read, but if you lube it unnecessarily, you're gonna make it harder on yourself. Heavy springs and slippy pins aren't a good combination to work with.
