Key quotes to provide a summary of the replies on Dexterity - thanks a lot!
I guess, what I'm saying is, if you want to make a small game to test the waters, make sure it's similar to what you want to be doing in the future, just smaller.
Well, one advice is to aim to complete it in 2 weeks. Then you may actually have a chance of finishing after 2 months
One should not make a game or a software simply to aguerrir (gain experience) but make a product which is sold and which meets desires or needs of final player/user...
I think it is a good idea and it shows that you are, at the very least, aware that there is more to it than (simply) game design and coding. I do believe that it is better to take on a smaller project but polish it really well rather than a half-baked larger project.
Indeed, making a game "sellable" can take a lot of time, compared to a game that just "works"... Anyway, that's a good idea to start with a very small project IMHO.