no probs Nik good advice 
notoriousquirrel,
the walk is after what distance and at what time of the phase? As I said it really depends on the timing. For intsance day 1 of my SPP will have me doing 4 x 60 with 2 mins rec versus near the end of Phase 1 where I’ll do something like 2 x 300+80 with + = 90 sec and no less than 30 mins between ‘sets’.