What are the most favourable conditions for the working class under capitalism?

It is often said capitalism from a left wing position is a awful, evil and exploitative system but I’d like to examine which conditions under capitalism would be favourable to the working class for winning concessions and gaining under the system not that they could ever really gain but for a time gain bit on their employing masters.

In Karl Marx fantastic pamphlet wage labour and capital the last chapter describes this brilliantly for me.
As we know the interests of labour and capital are in total opposites of each other and fighting in two different directions.

As Marx’s chapter 8 of wage labour and capital quoted here shows us
“A rapid growth of capital is synonymous with a rapid growth of profits. Profits can grow rapidly only when the price of labour – the relative wages – decrease just as rapidly. Relative wages may fall, although real wages rise simultaneously with nominal wages, with the money value of labour, provided only that the real wage does not rise in the same proportion as the profit. If, for instance, in good business years wages rise 5 per cent, while profits rise 30 per cent, the proportional, the relative wage has not increased, but decreased.
If, therefore, the income of the worker increased with the rapid growth of capital, there is at the same time a widening of the social chasm that divides the worker from the capitalist, and increase in the power of capital over labour, a greater dependence of labour upon capital.
To say that "the worker has an interest in the rapid growth of capital", means only this: that the more speedily the worker augments the wealth of the capitalist, the larger will be the crumbs which fall to him, the greater will be the number of workers than can be called into existence, the more can the mass of slaves dependent upon capital be increased.
We have thus seen that even the most favourable situation for the working class, namely, the most rapid growth of capital, however much it may improve the material life of the worker, does not abolish the antagonism between his interests and the interests of the capitalist. Profit and wages remain as before, in inverse proportion.
If capital grows rapidly, wages may rise, but the profit of capital rises disproportionately faster. The material position of the worker has improved, but at the cost of his social position. The social chasm that separates him from the capitalist has widened.
Finally, to say that "the most favourable condition for wage-labour is the fastest possible growth of productive capital", is the same as to say: the quicker the working class multiplies and augments the power inimical to it – the wealth of another which lords over that class – the more favourable will be the conditions under which it will be permitted to toil anew at the multiplication of bourgeois wealth, at the enlargement of the power of capital, content thus to forge for itself the golden chains by which the bourgeoisie drags it in its train.
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Marx is explaining that the greater growth of capital and the capitalist mode of production is in an upswing and is increasing its means of production to a point more workers can be employed from the mass reserve army and the workers can therefore go on the offensive within the trade unions to fight for better working pay and conditions. As socialists we look to expose the capitalist system at any chance we get but it’s a two fold approach from what I can tell when the capitalist system is in decline as we are now the system becomes far more exposed and workers can realise how little stake in society they really have whereas if the capitalist system is in a incline the workers can gain more as a slice of the pie but find it harder to recognise the contradiction of the system as they are benefiting from in the short term.
As the rich get richer the poor get constantly poorer even during the so called better times. So my argument would be even though an upswing in the capitalist system can benefit the workers in a sense this will not challenge the contradictions of the system and ultimately do nothing to defeat the wage labour system and lead to a breaking of the workers chains for their ultimate road to freedom.
But of course workers would prefer periods where they can go on the offensive and gain rather than periods they are set to defend what they have gained and to not loose anymore.