Wouldn't most males be required to serve in some extent?

Yes and no.

Fyrd service isn't strictly 'conscription' as we understand it in the modern sense. To a modern audience, the idea of conscripts has connotations of WW1 or the US Draft in Vietnam, of call-up papers and lives interrupted. The most probable nature of Fyrd service was somewhat different to this, and indeed to a number of theories which had previously prevailed over the last century and a half. An excellent summation of Fyrd historiography and current models by Gareth Williams can be found in Baker, Brookes and Reynolds' Landscapes of Defence in Medieval Europe. Previous models of the fyrd have held that it was open to thegns and Freemen (a model based heavily on the pre-Fyrd military and depending on a Victorian conflation of free men and Freemen, but which simply isn't mathematically viable), while ideas of a centrally-organjsed standing army are based on a frankly optimistic estimation of state authority and logistical capability. Instead, the raising of the fyrd was, essentially, a simple expansion of the dues of military or pseudo-military obligation further down the social hierarchy than had previously been the case, and functioned a further replication of the gesith, the associations which formed the semi-formal basis of Early Medieval English armies and, to an extent, civil society.

The gesith was, originally, the close band of warriors and followers who accompanied a king in his immediate retinue. As kingdoms expanded, these were the King's Thegns and Ealdormen, who provided military service in return for land, wealth and status. These King's Thegns and Ealdormen in turn raised gesiths of their own, and so on, so that pre-Fyrd armies largely consisted of a network of thegns and occasional Freemen who owed service upwards ultimately to the king. The Fyrd reforms essentially just further replicated this network of loyalty downwards, so that lesser thegns and Freemen who previously were obliged simply to perform military service themselves were now expected to raise a gesith of their own from those who owed them an obligation, and that for their tenants, a military service obligation replaced, or was added to, their prior rent service obligations.

What this means in practice is that, while the fyrd was organised at the shire level, it was most likely mustered at the Hundred or even the Tything level as a series of small warbands, which then coalesced into a larger formation. At Brunanburh, for example, Æthelstan is able to distinguish the contingent from Malmesbury specifically within the Wiltshire fyrd in the West Saxon elements of his army. The Battle of Maldon illustrates that English leaders fought in the shieldwall alongside their men, and knew them personally, while Strickland's work on the Lithmen who served in the maritime equivalent of the Fyrd in the Cinque Ports region (Strickland, Anglo-Norman Warfare) suggests that they were prominent and esteemed individuals within their community. The members of a Fyrd warband were therefore likely to have been specially chosen as the most capable and dependable fighters within a community, and stood likely to gain both financially and in terms of status from their service.

Other members of the community would still have provided 'national defence' services, but in a more peripheral role. Documents such as the 11th Century Rectitudines Personarum Singularum illustrate what forms those services might have taken. Individuals who didn't serve as fyrdmen or lithmen may have carried out burhbeorht or bryggebeorht - the maintenance of burghal defences and military roads, and bridges - or stood as seaweard as a coastguard watching for approaching ships. Similarly they may have stood as part of the general weard, manning watchtowers and beacon sites in order to pass alerts to burghal fyrd garrisons and local populations. In more specialised sites such as the Mercian logistical hub at Stafford, service may have included the industrial-scale baking of loaves and bannocks, production of Stafford ware pottery and butchering of meat to provide supplies to the garrisons.