My friend (banjo player) and I jammed last night.  Started off the evening with three rib-eyes (rubbed spicy montreal steak on two and the mild montreal steak on one).  Cooked them up to between rare (for his wife) and medium rare for the other two.  Put 6 marinated portobella mushrooms (three is balsamic vinagrette and three in Italian dressing) on the grill.  Two bunches of asparagus and grilled them also.  The dinner was great and a wonderful way to start the evening.

After dinner and clean up, we broke out out instruments.  It's been about a month since I played (busy with work).  Played:
I Know You Rider
Deal
Midra Rua (Pogues song)
Old Joe Clark
Nashville Skyline Rag
All Along the Watchtower
Walking Cane

Unfortunately, I lost a majority of my callouses on my left fingers so towards the end of the night, my finger tips were really startin to bother me (not hurt, just that the strings were leaving an inpression in the tips and I could not press the stings down enough to fret notes).  

I think from now on, I'm going to make the effort to at least play for 15-30 minutes a day.

It really does suck not to have your fingers in shape.  I also feel sorry for a beginner that's really gung ho and wants to practice three hours a day and can maybe manage 20 minutes at most for the first three months.

I play "I know you rider".  One of the few songs I attempt to sing.  I have to admit that I play it very much influenced by the GD version, key of D, kinda upbeat drive, sus4 vamp on D between the lines.  It's a really good jam tune.  I like the key change from (I guess) D mixolidian to C major on the third line and the passing Em going back to D at the end of the line.

Definitely get your mando out of the case once or twice a day even if just for ten minutes.  Makes a huge difference.  At least your chops don't atrophy.  Then practice if you happen to have a good chunk of time.

One other thing I noticed is that my mando went to sleep.  I'm not sure if it was the fact that I have not palyed in a while and lost the technique or if it "went to sleep".  Most likely it was a combination of both.  I have been playing it for about 15 minutes (as you mentioned).  I can't believe that I spent years developing callouses and in one month, they're gone  

cool thing was, I told my friend about not playing for a while and he said play until you can't.  We did that and then would take about a 15 minute break.  Start jamming again, break, jam, etc.

I'm going to his annual party in about a month so I need to get some hardness in my fingertips.

I like to take my mando out of its case in the morning and practice a few minutes before work ( I work out of a home office). Then I sit it on a stand to leave out for the day. Since the mando is in the Music/TV room, I'll sit down to relax in front of the TV. During commercials, I'll mute the TV, reach over, pick up the mando and noodle for awhile.

That will usually get me started in my practice routine and I'll turn off the TV (usually nothing on anyway). If I don't feel like practicing, I'll just noodle or work on a song I'm trying to improvise.

Its a matter of habit to pick up your mando and play it. I'm not a professional, so I can do what I darn will please, but I do want to make progress so I try to stick to my practice routine atleast five days aweek.