Personally I like the length of SG games and if anything for my preference they are almost too short in some cases, it does depend on the map (underwater games go way too fast in my opinion) :P on the other hand though everyone has their own preference and i can understand what you mean because it can be frustrating especially if you are like me when you use 2 or 3 chunks and you just end up mindlessly wandering around hoping for someone to appear.
Personally I feel instead of trying to speed up games I'd rather there be more places to explore to make the game interesting for a longer period of time but not long enough to just waste too much time, Easter eggs and secret items/areas and things like that. I feel like the maps need more "personality" in a way, a story.
I think bringing deathmatch back in solo would be a good idea with a proper map themed arena and in teams have borders that come in at 10 and hit centre at something like 14-15 minutes or when there are 6 players or 3 teams worth of players left in the game (idk, those were just random numbers I picked). It would give more time to expirience the game but would also give a quicker end so you don't have to run around and hope.