If you want to train to get stronger you need to learn to manage your general fatigue through cycling intensity and volume. High intenisty work (ie +90%) ie Westside ME sessions don't generally give you the DOMS of BB style training but dose generally 'batter' you more and give rise to more chronic type fatigue.
If you are doing ME sessions, a la Westside, then you probably need a planned break pretty frequently. This could simply be dropping the strength work, whilst continuing the BB work every 5 weeks or so. So this is not a total rest week rather a reduction in intensity, or volume, or both. A more traditional linera progression type cycle allready has lighter weeks built in.
Either way it takes some trial and error to know what work to do and when!
im havin good days followed by a few bad ones at the mo so im not switched on for consistant hard trainin!!
'Bad days' are just as part of training as good days. The important thing is getting the appropriate work done each week, rather than trying to pb every session. As you mention consistant hard training is the key.
If I was feeling rough I'd just cut back on both volume and intenisty for a week. As you catually siggested do a few purley DE sessions. Speed work (but not a big volume as normal), 1-2 light assistance lifts and get out.
As an example this sat I was still recovering from my comp last sunday and I just worked up to approx 70%x5-6 on the bench and squat, then 50%x5x3 for down sets, and then finished with a bit of light cable rows.