Number of synthetically observed planets from our simulations (top) and the period ratios of adjacent planets (bottom) for a mix of planetary systems that includes 2% stable chains and 98% systems that underwent instabilities. The colors are the same as in Fig. 4. Both sets of simulations give a nice match to the number of detected planets, but the period ratios are matched better in the high-viscosity case, compared to the low-viscosity case.