Bowling as a youth with a 12 pound ball, I was able to bowl several all spare games. As an adult, using a 15 pound ball, I can only remember doing it once and it was on a sport shot (WTBA Tokyo). I would for the most part either flat 7 or go high leaving the 2-4-7. I shot 177 - and it was maddening and I didn't have an answer (obviously I'm not that good).
Anyway, I think it would be incredibly hard to have an all spare game on a house shot for a bowler throwing anything over 14 pounds with an average 200 or higher. However, a bowler with low ball speed, no revs, and a decent amount of accuracy could do it on the regular. I bowled with a woman who fit this description to a t - she averaged in the 160s and did not strike often although she was around the pocket most of the time.